Shortly after his conversion, Prof. Scott Hahn noted that he was confessing the same old sins time and again. He mentioned that to the Priest who asked him, “What do you want, new sins?”
Do not become discouraged, as the devil’s main weapon against faith is discouragement. Be resolute. If there is some element in your life that triggers this sin, do what you can to remove that triggering element from your life. Advent can be a powerful season against sin. Even though it is not strictly about fasting, consider giving something physical up and taking something spiritual on.
If you do not currently:
The Rosary is a wonderful devotion that will help you spiritually. Consider going to spend time with our Lord at adoration. Place your sinfulness before Him, as generations past and present have done.
Just some thoughts.