Sorry nobody has replied yet... I really can't offer any solid advice here since I have not experienced this. How old is your liner? If it were my pool, and I was within a few years of replacing the liner, I would just keep an eye on it and wait it out. Otherwise I would probably do some investigating over the course of this season and hope to find the leak (or at least a suspicion of where it is). Hopefully someone else here can provide a better answer.