Sammich, if you've had the Hep B series before and tested positive for anti-HBs in the past, your school may not require you to get re-vaccinated. There's a ton of research out there supporting the fact it's actually quite common for individuals to have decreased (or even undetectable) antibody levels years after being immunized. Long-term protection (estimated to be ~15-25 years) is apparently conferred through the maintenance of memory B lymphocytes even in the absence of antibodies. So immunocompetent individuals should not require booster doses/another full series of vaccines despite low or undetectable anti-HB levels.
I pointed this out to my med school's student health department and attached supporting articles I found on PubMed and asked for them to double check school policy. The student affairs officer then let me know that I was exempt and didn't have to get the Hep B shots again (according to titers I just got, I was also "not immune"). I only had to provide them with my previous lab report showing I tested positive for anti-HBs. If you didn't have previous titers drawn, but have proof that you at least received the entire Hep-B series, I would still ask if they can excuse you from getting the shots again. Worth a try.