Can you fix candy melts after you get water in them and they get all clumpy?
Probably not. Although they're not real chocolate that requires tempering, they do seize up when water gets into them.
You can "try" adding a tiny bit of vegetable oil (perhaps an 1/8th tsp. at a time) and microwaving on 50% in 10 second bursts, stirring each time.
They may be OK for flat applications, but I can't guarantee that they'll set up perfectly.
Try adding a shortening to them a little at a time until they smooth out. If you add too much it will thin the candy out so don't add a bunch at once.