I agree with many others about your decision to keep or not. If you want to keep it, check out the work of Julia McLeod who uses sheer fabrics to cover old quilts - you retain the old top but add protection. Basically she pieces sheers, matching the block sizes in the original top, lays the sheer layer over the old top and ties at block corners. If you don't want to re-stitch the seams in the old top, this method could be used with a little extra machine or hand quilting to stabilize the areas where the seams have come apart.
If you are a member of The Quilt Show.com, check our her portion of show #3709