you can not ever donate blood if you test positive for the antibodies even if you dont actually have hep c, its just the way it is, safer for everyone. but if you have tested neg for hep c so much unless you continue to do things that expose you to the virus you dont have to continue to test. you will always have the antibodies but those antibodies wont turn into hepc if your body already fought it off. they are just there to show that you were exposed at one time.
You will always have the antibodies, forever. The level of the number means nothing, they will always be present and show up on blood tests and that is all that matters.
Congrats on not having HCV, the answer your question on lowering antibodies is no