No, as Lucien wrote above, ne pas is used before an infinitive, not the present participle. So it would be "en n'étudiant pas mieux" and that is accepted. But reviser is better for studying for an exam.
étudier vs réviser. I had thought that the former meant to study and the latter to review. So is one were preparing for exams one could do either but I think the English translation would have been better with "to review."