Repair or Replace The Shower Pan?
One way to solve the leaky shower pan problem is to have the entire shower floor ripped out along with several rows of wall tile. This procedure is costly ($600- and up depending on the size of your shower), messy and in my opinion unnecessary. 99% of the time a new shower base and pan is built in the same manner as the old one; eliminating expansion joints at all the seams, clogging the weep holes in the shower drain, along with not sloping the shower pan membrane.
It's a wise idea to have the contractor draw you a picture explaining in detail of how the pan will be constructed. What is going to be done different? How do we compensate for movement? Will there be some type of sealant where walls meet walls and walls meet the floor? A lot of time contractors will use acrylic based tub and tile caulking to hide cracks. Ask if they realize that most water soluble caulks dissolve in the shower and are not meant for stall showers.
Option two is to replace the shower for a cost of $1200- and up. I you decide this is the way to go, ask the contractor for a blueprint of the shower design. Insist the pan be built by the specifications that are listed on my web page Proper Shower Pan Installation.
Your third option is to hire a handyman, spouse, friend, or neighbors nephew's son who does tile work on the side. Next, arm them with a tube of misc caulk and have them gook up the place. Or hire a grout restoration company who will cosmetically make the cracks look pleasing, yet really have no real knowledge of tile problems. Cosmetic restoration is strictly cosmetic. If something cracks, the odds are that the same area will crack again in the future. Sometime they will use an acrylic caulking in the jionts that will prevent cracking for a very short while. Remember, hot water dissolves acrylic caulks and silicone will not stick to anything remotely wet.Leak Repair is an art that takes many years of training along with experience. A year or two of using a caulking gun does not constitute experience. Anybody can lay a nice tile job, but do they understand why showers leak, why cracks in the grout develop? Ask about the benefits of the different types of caulking such as: silicone, polyurethanes, acrylics, and epoxies, and when it's best to use each type. 90% of the work I do is fixing leaky shower pans. I also have 25+ years experience with tile repair and restoration.