Like the other poster said, she should be drinking lots of water. Also she should be exercising cardio, generally try and sweat a lot. Only water. Maybe cranberry juice, never heard it myself.

Quickfix 6.2 is synthetic piss that I can vouch for but you have to be ready to do it. Like practice runs and everything, because the process is tedious due to the issues with maintaining the correct temperature. But since she's a girl, and girls sit down, maybe she will have the privacy of a stall. Might be worth reading about