The following procedures can be used to repair a cracked tile without having to replace it:
To get rid of any dirt or debris, properly clean the broken tile.
Try filling in a minor fissure using silicone-based grout if it's possible. Using a little tool like a toothpick or butter knife, just apply the grout to the crack and smooth it out until it is level with the tile's surface.
Use an epoxy repair compound if the crack is bigger or the grout approach did not work. These are made specifically for patching cracks in tiles and can be purchased from a hardware or home improvement store. For mixing and application instructions, refer to the manufacturer.
After the repair compound has cured, softly sand the patched area using fine-grit sandpaper to make it smooth and uniform with the surrounding tile.
The tile should then be cleaned and sealed to help prevent further damage.
Remember that they are only short-term solutions, and the crack could eventually resurface. It could be required to replace the tile if the damage is extensive or the crack is significant.