Reclaiming a word means stripping it of it's negative baggage and giving it either a neutral or positive meaning. The most common example is the word Queer going from a slur to a descriptive term for non cis-het people.

My personal pick would be returning the term "incel" to it's original meaning of "involuntary/involuntarily celibate" or someone who wants a relationship but doesn't have one, because the word is currently associated with the few tens of thousands of extremists who occasionally commit terrorist attacks, consider the redistribution of women reasonable and created the black-pill, but the amount of men (and realistically also women) who would consider themselves as wanting a relationship but not having one is much higher than a hundred thousand violent extremists, and if they could all describe themselves as incels, I think that would help steer the conversation about wanting a partner and not having one away from the extremists and to the much more numerous pool of mostly young people, seemingly mostly men who just want a partner and can't have one and usually mostly just feel bad about it to varying intensities. It wouldn't completely detach the term from cringe online right tropes as a lot of the dudes who can be described as incels often tend to fuel the kind of "women aren't real"/"Girls don't exist on the internet" culture that makes complaining about dating so 'lame'. (As in, the default reply is "just do basic self-improvement it'll put you ahead of most people lol".)

Another term I would reclaim if I could is the Red-pill/Blue-pill dichotomy with becoming red-pilled either being a joke about some vaguely red pill used to transition or as a shorthand for adopting leftist beliefs, mainly because the creators of The Matrix were Trans women who intended the movie to have a strong Trans subtext, and red is usually a leftist color instead of a conservative one, so becoming red-pilled meaning becoming a leftist is more intuitive in most places.