I recommend that you replace the entire line and you will never have a problem. My company offers a lifetime warranty on materials and workmanship for water line replacements. Here is the caveat - you don't need one. With water line (poly) pipe buried below the freeze line, it will never go bad in our lifetimes unless damaged by an outside force of some kind. The only reason to put a time limit on a warranty for water line is to keep the plumber from having to make a bunch of free service calls to fix a different problem. That is why repairs have a limit. Splices can fail in a few years and if you already have a problem with your water line in one place, you will soon have another problem, and another and another.