Maintain the previous responder. Also, probably, you should have kept your student: it is unlikely that the guards at your university remember who graduated and who is still studying. I had so many friends)
You can either apply again, which is unlikely to be pleasant, or go to university for free students. If you have already studied at the university and have a diploma, then you will most likely be given the right of a free listener, which gives you the opportunity to attend lectures of interest just for yourself, without further passing exams and writing term papers.