Is it true that there have been cases where patients have tested negative for hsv-2 after a year if treatment when they were previously hsv-2 positive?

HSV: Hsv tends to stay with you for life. Hsv2 can be negative when not having an active disease of when the shedding is low.

It depends...: If the original test positive detected the virus from a genital area sore (culture or PCR), you definitely have HSV2 and your recent negative (blood?) test is false. If the first was a blood test, most likely that one was false and you may not have HSV2 after all. Maybe more to say if you would like to post a new question with details, including numerical results of blood tests (both HSV1 and 2).