If God has wiped your slate clean ,there is not sins to confess.Because I have repented of my sins, they are all taken care of, punished on the cross, and so I am now declared righteous in God's sight. I cannot be made unrighteous, even though I may sin occasionally, because all my sins are forgiven! But when I sin, I confess it to God and thank Him for His great grace, and for my complete salvation in Jesus Christ, and for His complete forgiveness, and that He has wiped my slate clean.