Sarahphoto,
I'm not sure you're getting answers to your specific question.
Here's mine
My short answer is, "Yes, the prints will last (longer) if you re-wash them properly."
What you will not change, however, is any damage that has already been done to the print, either visible or invisible. Discoloration is usually permanent. Keep in mind,also, that there may now be invisible non-soluable silver compounds in your print that may yet discolor at a later time. There's nothing you can do about that.
That said, if the problem was underwashing (and even underfixing) you can (refix and) wash the print at a later time and remove all the soluble silver thiosulfate compounds and thereby extend the life of your print significantly. Of course, the sooner you get the print properly (fixed and) washed, the less damage is likely to occur in the future.
I would recommend soaking the prints, then refixing in fresh fixer, a treatment with a wash-aid followed by a full fix in fresh fixer. While the result may still show defects, the print should not be much more permanent than it was prior to proper washing.
That said, if there are print defects, the better solution may be to simply make another print and process it properly. However, it it is a "one-of-a-kind" and you only have the print, then go ahead and do your best to save it.
Hopes this "clears things up,"
Doremus Scudder
www.DoremusScudder.com