It should be sufficient to reseal your shower every one to two years, depending on how frequently the shower system is used.
Opt for a shower sealant labelled ‘Tub & Tile’ or ‘Kitchen & Bath’ when sealing tile and grout.
Certain types of tiling can prove too thick to properly absorb the sealant, so test the process on a small defined area to begin with.
If the tiling soaks up the sealant successfully, you can seal the full shower enclosure.