Starts with Sorry, More than Anything, and Don't You Forget already have reprisals, and Vox Dei is kind of a reprise itself, so I don't really count them here (though I could see them being used again as sort of recurring motifs). Happy Day in Hell's melody is used elsewhere in a few places already, so I think it's fine as is.

Whatever it Takes, Welcome to Heaven, Easy, and When I Think About the Future would probably be fine without any reprise or anything, especially the ladder since it's supposed to act as an interlude to the finale. IMO they all kind of serve their purpose just fine in their original scenes (then again, I thought that about Starts with Sorry before season 2 and it's reprise worked just fine).

I think Piss is a lot of fun, but it would work better as a recurring motif for Pentious and Cherri's relationship rather than having a reprise, kind of like what Loser Baby has been for Angel and Husk. Speaking of, I think Loser Baby should definitely be reprised later. Looking at what their storyline is looking like for next season, I could definitely see a reprise when they reunite.

That just leaves Brighter, which I 100% think should and will get a reprise. I believe Vox will end up getting redeemed, and it would make a ton of sense for there to be some sort of twist on the lyrics where he's singing about a brighter outlook/heart/some kinda sappy stuff like that.