13 year old has to argue for school uniforms in a class debate. She hates uniforms

Debate in her class next week, sides decided by draw, and of course she got 'school uniforms are necessary'. She's been campaigning against uniforms since grade 6, so she came home furious, saying it's unfair and she'll 'lose on purpose'. I told her arguing a side you don't believe in is the whole point of a debate. Got the eye roll. Emi cheyali. Is it worth pushing her to prepare properly, or do I let her find out the hard way?