Don't bother fixing a spilled-on mousepad.

No. Once the liquid dries, the foam or rubber layer underneath is permanently warped. You can try a few things (ironing with a towel, soaking and pressing flat), but in my experience, they never lie perfectly flat again.

Coffee or water seeps into the padding, then dries unevenly. That creates a bump or wavy spot that you can feel while mousing. Even if you flatten it temporarily, it’ll come back after a day of use. The texture of the surface itself might also be stained or rough now.

Your time is better spent ordering a new mousepad. They’re cheap. Some decent ones run $10–20. Future you will thank present you for not fighting with a ruined pad.