If your shower has a shower pan replacing just the pan is possible but not always advisable.
Replacing shower pan in tiled shower.
The point of having a shower pan is one part versatility and one part convenience.
Improperly installed shower floors can allow water to seep through the floor causing cracks or failure of the tiles which results in water leaking below the.
Shower pan liner replacement ceramic and marble tile showers john p.
How to replace a tiled shower floor.
Matching your tiles will be the problem though in most cases.
No point in tearing out entire shower when it fails the issue is almost always just the pan.