Should I just give up?

I keep doing the same sin over and over, and repent every time. God must not think it's sincere. I do it on purpose, but then regret it as soon as it's over. But whenever something tempting comes along, I ignore Jesus telling me not to do it. I don't know why I do this...I don't want to, but maybe I apologized too much and I'm not really doing anything to stop this sin..