My doctor put me on 30 mg of cipralex because while 20 mg worked great for five months, it stopped working. Is this dose too high?

No. Reasonable dose change given your situation. Wonder when you started Accutane and if that could be causing some depression rather than the Lexapro (escitalopram) 'stopped working.' Maybe after Accutane course, you'll be able to lower Cipralex dose. Hope you feel better.