Was there such a thing as "retro" fashion prior to the 20th century?

Yes and no.

On the no side - today, it's acceptable (even stylish) to go all out and dress in actual vintage clothes or reproductions, but before the 1970s-1980s, doing this would have been extremely unfashionable and eccentric. The idea of wearing "retro" clothing was silly.

But on the other hand, from the 1790s on, fashion has been mostly about historicism. From a modern perspective, the actual impact of historical styles is fairly small, but on closer inspection the same model of repeating trends is prevalent.

Neoclassicism began in architecture earlier in the 18th century, and became highly fashionable in furniture in the 1770s-1780s - it's not surprising at all that it then gradually moved to clothing. The first stirrings of it there are in the chemise gown, a flowing white garment held in with a sash, that was worn in close-knit aristocratic and artistic circles and then spread out to the general population. A medieval/Renaissance/gothic influence followed (beginning around 1805 in France, 1810-1815 in Britain), bringing in elements like slashed sleeves, padded shoulder rolls, and eventually fuller skirts and pointed waistlines.

While gothic elements continued to be incorporated into women's dress, others from the baroque era and ancien régime started to really come back in the late 1820s - and while the late 17th century didn't stay in fashion longer than those very full sleeves and broad hats of the early 1830s, in various ways there was a definite intention of emulating stylistic elements of the 18th century. They fluctuated in popularity with the gothic ones (and kind of overlap - eg the pointed waists could be and were taken by either), but eventually won out, and fashion descriptions reference Marie Antoinette and the periods of Louis XV and Louis XVI through the end of the century. This is most visible and intentional during the bustle eras of the 1870s and 1880s: Dolly Varden hats, split overskirts, a skirt foundation very similar to that used in the 1780s (yes, the bustle actually goes back that far), elbow-length sleeves, pointed waistlines, heeled shoes ...

Some early 20th century fashion actually goes against the historicism trend - the stereotypical Edwardian poofy gown doesn't come from any historical basis, but it was fairly soon changed to reflect interest in Neoclassicism (neo-neoclassicism) with higher waistlines and slimmer lines. During WWI, full skirts reflecting 19th century styles returned briefly. Fuller sleeves with big shoulders, worn in the 1820s-1830s and brought back in the mid-1890s, came back in the 1930s. And so on.

Do we know of a fashionable queen who "brought back" the bustle/pointy hats/Spanish lace/see-through chest panels/a funky kind of obi knot as an homage to previous fashion generations? A king who brought back his great-grandfather's wigs?

I just want to speak to this in a slightly off-topic way, because it's a Thing with me - fashion history is very commonly talked about in terms of "fashion icons", generally queens, who invented and disseminated fashions, but in reality it very rarely worked this way. As I mentioned above with the Neoclassicism of the 1790s, fashion is related to other forms of art and design, and trends in those usually seep into dress as they change what appears beautiful and attractive. Research rarely bears Great Woman (or Man, once you're in the era in which couture houses existed) history out in this field - even the New Look turns up in many collections in 1947, not just Dior's. It's not common for any style to become popular because of an important person deciding to bring it in.