While all of the above is good advice, the best thing you can do for yourself is to discuss your plans with your instructor. If you plan to delay finishing your class, your instructor will be able to advise you on what he/she will want you to do to "refresh". If you plan to finish your course with a different instructor, your previous instructor will need to provide you with a referral.
Overall, your instructor knows far more about your situation than anyone on Scubaboard and should be able to give you the best advice.