I cure this problem by literally glueing the tape back down using border adhesive. I use either a brush or a 35cc vetinary syringe to get the glue behind the tape and then smooth it back down using a small taping knife. When its back down, wash the excess glue off with a sponge and clear water and allow to dry for several hours. You will probable find that you'll need to remud the tape with joint compound. Apply the compound in at least 3 thin and successivly wider layers to feather off the joint. When dry, sand with 120 or 150 grit sandpaper, prime and repaint using good quality materials. I'd recomend using an oil primer if this is a bathroom that is constantly used for hot steamy showers. If mildew is a problem, use Zinnser's "PermaWhite" paint for a finish, it will stand up to the moisture and it will not mildew. If you do use PermaWhite, you must use an oil primer under it. If you don't, the paint will peel where you patched the tape.