If it's on the edges, it could be as much from bad storage...if it's overall, in the image area--there are ways to bleach out a print and redevelop it, among other things. All this falls into the realm of conservation though...I don't do any of this at work, we mostly stabilize (and copy for old photos) objects, because restoration isn't exactly kosher in the archive/museum business...if there were other problems from storage or the environment with a print, then reprocessing them just opens a whole new can of worms. Better to copy first, then try to do the work. That way if you mess them up, you still have something. Our approach is strictly hands off though--literally--any work is done by professional conservators. ...from my "work" point of view, I'd say either reprint them (if you can) or copy them. If the prints were a couple of years old, that's one thing. But they're getting on 30 now, and while that's not old, I copy "artifacts" that age everyday...'course, they're yours, you can do whatever you want to them.
btw--a good copy neg, or dupe neg, can be very close to the original in quality, it's just most people don't put the time or effort into making good copynegs...