Long ago CUNY had a low admission bar and a high graduation bar. This meant, of course, that many students dropped out. In your case, students choose to pay tuition and not do the work. What is the external pressure on you or the dean or university to make things easier for these people? I think there should be a reverse feeder school idea: enroll in a university where standards are high, if you do poorly then transfer to a community college. That way a degree from that university is a signal for quality.