It all depends on your state, their certification requirements and the NR, but you likely don't need a refresher yet. You will need to complete a refresher course within the first 3 years of your certification, most likely, in addition to a certain amount of continuing education. It certainly doesn't hurt to begin early, especially if you feel rusty on your knowledge, assessments and skills...
Oh, also, I'd like a refreshment course anytime, maybe I could become a bartender.