Answer:
The power of Christ’s blood is certainly powerful enough to wash this sin away, even after repeated offenses.
However, the Bible tells us to repent of our sins and repent literally means to turn from and go the opposite direction. It is only for God to judge, but it seems as this person has not turned from and walked away from this so it is questionable if they are repentant.
The Bible also tells us …1 Peter 1:16 Because it is written, Be ye holy; for I am holy.