Napoleon was defeated in 1813 in the Sixth Coalition War, and he was offered (in 1814) to keep the French throne in exchange for the return of lands conquered by France after 1792. He refused, was sent to exile and the lands were returned anyway (eventually, at least). why did he refuse? Was it pride? Was it not obvious that he couldnt hold on to the lands he conquered after he was defeated anyway? Wouldnt maintaining the throne present more opportunities to re-conquer those lands later? Did the succession of his son play any part in his decision? What was his rationale for refusing this offer?
Good question, there are many reasons.
There was little reason to trust the allies and anything they had to say. Alexander had betrayed the Treaty of Tilsit in 1807 in a multitude of ways, Austria had gone from ally of France, to neutral mediator, to enemy of France in a short period of time. Metternich had the Emperor's ear and despite Napoleon being married to his daughter, would allow Metternich, who had lost much personally to Napoleon, to run the show. Prussia switched sides almost as soon as Napoleon was out of Russia. There were multiple traitors close to the Emperor's court like Talleyrand, and at least one plot to steal the throne from within France. The only sure way to protect his throne, and more importantly to him: his son's throne, was to fight on.
They all wanted everything back that Napoleon, and the Republic, had taken. Napoleon however had gained much of this for France in the first place, and as First Consul and then Emperor, sworn to defend it. He personally helped set up multiple republics in Northern Italy, and when he became First Consul, the Batavian Republic in Holland had already been a part of French territory for years. He wasn't about to give up this territory if he had a chance to defend it, and even though he did lose in 1813, and the chances were slimmer in 1814, he did still have a chance. At the close of the fighting, Wellington received a very bloody nose from Marshal Soult, Marshal Davout still held Hamburg and Napoleon's nephew (Josephine's son) Viceroy Eugene was conducting a brilliant defense of Northern Italy. All the while, Napoleon was holding off Prussia, Russia and Austria's primary armies.
If you examine the campaign in 1814, one that Wellington would call Napoleon's most brilliant, Napoleon did a fantastic job and may have, at the very minimum, saved the throne for his son if not for the betrayal of Marshal Marmont who gave his entire Corps of troops over to the enemy, which completely destroyed Napoleon's ability to negotiate a conditional peace. By giving up Paris with so little of a fight, Napoleon's campaign was rendered mostly pointless. By giving his entire Corps to the allies, Marmont completely doomed Napoleon's chances for his son.
I would not say that it was pride but his duty, it wasn't obvious that he couldn't hold it(he very nearly did) and his son's throne was indeed a very large part of his decision making.
Your comment about reconquering is probably exactly what the allies were thinking in 1815. Napoleon this time, upon returning from Elba, was the one who promised that French territory would remain in the pre-1792 borders but the allies rebuffed him and declared him an outlaw.
And in another parallel: in 1815 Davout, Napoleon's most skilled and trustworthy general, was left in control of Paris, since Napoleon was to again be outnumbered massively, he knew he needed to be able to maneuver around his larger opponents without having to worry about Paris falling or at least giving its armies over to the allies.