I know binders wear out, I'm guessing that's because they stretch out over time. I know this probably isn't possible with zelcro LOL velcro* binders, but has anyone ever tried taking them in to "renew" the binder? Or even just taking in seams just so they fit better?

Fabric can only stretch out so much, so taking it in more you'll lose that bit of give that'll make it comfortable and not constrict your ribcage so much. You could try it, but you'd definitely be sacrificing whatever comfort you may have with the binder.