A cracked tile doesn't always mean replacement. If the crack is cosmetic and the tile is still firmly bonded, a repair filler can make it nearly invisible.
Clean the tile thoroughly. Use a utility knife to very lightly widen the crack for better adhesion. Mix the epoxy or tile filler per instructions and press firmly into the crack with a putty knife. Smooth flush and remove excess immediately.
Once the filler is dry, apply touch-up paint if the color doesn't match. Finish with a coat of clear sealant to protect the repair.
If the tile is broken into multiple pieces, is lifting from the substrate, or multiple tiles are cracked in the same area, replacement is the better fix.