Shower resealing is the process of removing the previous tile and then adding a new sealing product to prevent future leaks. This can be accomplished by either cutting out the old tile, sanding off the old tile and then sealing it, or by spraying a sealer on the shower walls in an effort to make it waterproof. Shower walls are typically the weakest point in the shower. Water can leak through here to other areas of the house as well, but leaks can be more easily tracked from the shower wall to the rest of the house if there is a sealer applied. It is very important to apply a good quality shower sealer when doing a full remodel or when simply repairing the leaky pipes.
In some cases, particularly older homes, the tiles themselves can be replaced and the walls repainted and this is another form of shower resealing. This is not recommended for all homeowners, as the seams for replacing tiles can be very small, and it is easy to break the seal between tiles once the repair is complete. If you choose to try this route, a professional should be consulted to learn if it is a good idea to proceed.
There are also kits available that will do the job for you professionally. These are great for people with previous leaking shower jobs and who want to try to fix the problem themselves. These kits contain everything you need to repair a leaking shower including the sponge, adhesive remover, sealant, tips and more. You simply mix up the adhesive and spread it over the area being repaired, working from the outside inwards. This method is similar to what a plumber would do with the problem, except it is done right in your home.