There really wasn't a comprehensive, cohesive pro-slavery argument in New England before slavery was already abolished. Probably the most thorough analysis of the pro-slavery arguments in Colonial America/United States is surveyed in Proslavery: A History of the Defense of Slavery in America, 1701-1840 by Larry E. Tise. His book has a series of tables which breaks down the common arguments, and which I have summarized in this previous answer. Seek out that book if you want to read more of it for yourself. In each table, Tise breaks down the arguments by geographical location and time period, and there isn't a particularly jarring difference between the defenses Northerners were giving than Southerners were giving. If anything, the Northern defenses were more skewed to what Tise characterizes as "Biblical Scripture", "Theology", and "Duties of Masters" (again, see my previous answer for more explanation). And the latter characterization has religious undertones as well, since Northerners often relied on the arguments that masters "must provide religious instruction" and masters "must answer to God for his treatment of slaves".

Even so, these arguments were slightly more popular than other arguments even among Southerners, so Northerners making them weren't hugely different in that respect.

Further, the emphasis on religion is likely a function of slavery defenses in New England and the North mostly coming from before the American Revolution, or in the early years of American Independence. As Tise explains, there really wasn't a fully comprehensive anti-slavery, let alone pro-slavery, argument being made until the Revolutionary period. There were what Tise characterizes as "Pro-Slavery Writings" before the Revolution, but what he categorizes in some of his tables as "Formal Defenses" didn't really develop until the 1780s, at the earliest, and most coming from the 1830s on. A third category, "Proslavery and War Sermons", mostly came immediately before or during the Civil War.

Thus, by the time any "Formal Defenses" were being written, New England had already abolished slavery, either immediately or by "gradual emancipation". There were a handful of pro-slavery "formal defenses" coming from the North, thereafter. But again, their defenses weren't markedly different from those being offered from the South.

But of the few differences, they are worth mentioning. Tise counts fifteen "formal defenses" that came from Northerners, all(?) after 1800. I'm too lazy to go through the book to find all the names and dates of these defenses, but Tise does focus on a set of four of them in one chapter, "Emergence of Proslavery Ideology in the North, 1831—1840". The four writers he focuses on are:

• Harrison Gray Otis (1765-1848), mayor of Boston

• Charles Jared Ingersoll (1782-1862), U.S. Congressman from Philadelphia

• James Kirke Paulding (1778-1860), novelist and U.S. Secretary of Navy from New York City

• Samuel Morse (1791-1872), inventor (Morse Code) from Massachusetts

While their arguments on behalf of slavery, again, aren't hugely different from those of Southerners, the few key differences are:

• They all made statements, either in their formal defense or in other writings, that they were very much out of step with their Northern contemporaries. Ingersoll would write: "In Pennsylvania we are none of us friends of slavery," as he wrote in defense of slavery. Morse would say that his fellow New Englanders accused him of being "as a Secessionist," unlike all his friends and associates.

• The all made statements that their defenses were motivated by a desire to preserve the Union. Paulding wrote in his book that he had been prompted to defend slavery on behalf of "whether THE UNION SHALL LAST ANY LONGER". One of Morse's defenses was entitled The Present Attempt to Dissolve the American Union, a British Aristocratic Plot. Otis accused the pro-abolitionist hardliners of treason attempting to break up the Union.

• There was also a common thread that, ultimately, it was none of the North's business, and the abolition of slavery was the South's decision alone. Otis was particularly concerned with this point. He thought the Union was one country, all starting out as slave states, and as such, the North owed it to the South to allow them to make their own decisions, just as the South had allowed the North to do. "I am desirous," he once wrote, "of leaving the affair of emancipation of your slaves to yourselves, to time, to the Providence of God."

Still, it shouldn't be understated that these Northerners were very much out of step with their contemporaries. As Eric Foner writes in Free Soil, Free Labor, Free Men: The Ideology of the Republican Party before the Civil War, anti-slavery, to whatever degree, was almost a given among Northerners for quite some time before the Civil War:

"Politicians of all parties agreed that northerners opposed slavery as an abstract principle, although they disagreed on the intensity of this sentiment. John C. Calhoun had estimated in 1847 that while only 5 per cent of northerners supported the abolitionists, more than 66 per cent viewed slavery as an evil, and were willing to oppose its extension constitutionally. Similarly, a conservative Republican declared in 1858, 'There is no man [in the North] who is an advocate of slavery. There is no man from that section of the country who will go before his constituents and advocate the extension of slavery.' Northern Democrats had the same perception of northern sentiments. Even the Hunkers of New York, who consistently opposed the Wilmot Proviso, refused to say 'that they are not opposed to slavery.' For as William L. Marcy declared in 1849, 'In truth we all are [against slavery].'...'The antislavery sentiment,' Hamilton Fish explained in 1854, 'is inborn, and almost universal at the North...'"

In summary, while there were a few scant pro-slavery statements made, and even pro-slavery-related pamphlets published before abolition occurred in New England, there was nothing approaching a pro-slavery ideology ever expressed there. What was expressed was mostly religiously motivated, with some white supremacy mixed in, as well as some "slavery isn't as bad as its opponents claim it is" in there occasionally, but often going back to the religious. Slavemasters had the "white man's burden" of Christianizing the heathens, and would have to answer to God for any mistreatment.

Largely, though, the pro-slavery writings that came out of the North were motivated by preservation of "the Union", the United States. Some Northerners, later to be characterized as "doughfaces", believed that the trouble with slavery were their Northern compatriots being so vocally opposed to it. If everybody would just shut up and let the South decide what to do for themselves, then the country would be much better off. According to their arguments, the Union was more important than the freedom and liberty of enslaved people, and Northerners were largely overreacting.