[Advice] I have to quit smoking for two (and a half) years straight. SOS

I'm in school, and live with my parents. My school is very small and private, and in their contract says that under suspicion, they have the right to drug test me. The process went as follows: -Friend got called into office first, told me to tell truth when they asked. -Literally 2 minutes later, got called into office. -Heads of school sitting across from me, ask me if I indeed did smoke. -I told the truth. This meant they would not give me any sort of trouble with the school for honesty and not having to waste money on a test to find out the truth, BUT... I have to be tested in 90 days, and then randomly for the rest of my years (2.5) there. Before you suggest the hair bleaching, fake pee, etc, I mentioned I live with my parents and attend an expensive school for a reason. Until, I graduate, they will also randomly test me to prevent me from getting caught again (which really wouldn't change anything if I did actually smoke again until then). Any advice, stories, tips, replacement substances (not a fan of synthetics or man made at all, I don't even really drink and react very badly to stimulants, which is why I love(d) bud), condolences, and/or your experiences are very welcome.