Active job

Bathroom shower tiling

I need my ensuite shower re-tiled. There have been cracks and gaps in the grout for over a year and water leakage has got beneath the tiles. I don't know the extent of damage but they need pulled up, cleaned underneath no doubt, and retiled. I'm unsure if there is a way to keep the same tiles and re use them or if they need replaced. The shower hasn't been used for 6 months or more to ensure that the area is dry beneath and now a workable space.