C.S. Lewis postulated that our sins never really completely go away. And although the Messiah redeemed us for our sins they are still before us during our final judgement.
We will still need to atone for those sins. The universal law of justice written in our hearts requires this. This is why the Father, for the sake of justice, could not simply forgive the sins of humanity but had to ransom his son on the cross.
True repentance is not simply "coming to God on death row" after "a final meal of fried chicken." True repentance and atonement requires as proclaimed in the Sacrament of Reconciliation: confessing our sins, doing penance, and amending our lives.
Lent is a time to examine one's life and affect a change that brings us closer to the Creator.
True repentance allows us to face our sins, embrace God's forgiveness and acknowledge that yes, those sins were once me, but no longer. Only then, when one truly comes to God accepting all of the responsibility and consequences for past sins, shall "None of the crimes he committed shall be remembered against him; he shall live because of the virtue he has practiced."