There is great blessing in repentance. Consider what the psalmist wrote in Psalm 51:
Hide your face from my sins, and blot out my iniquities. Create in me a clean heart, O God, and renew a right spirit within me. Cast me not away from your presence, and take not your Holy Spirit from me. Restore to me the joy of your salvation, and uphold me with a willing spirit. (Psalm 51:9-12)
The beautiful thing about the gospel is that in Christ, all of this is true for the believer:
Colossians 2:14 says, "by canceling the record of debt that stood against us with its legal demands. This he set aside, nailing it to the cross."
2 Corinthians 5:17. "Therefore, if anyone is in Christ, he is a new creation. The old has passed away; behold, the new has come."
Ephesians 4:30. "And do not grieve the Holy Spirit of God, by whom you were sealed for the day of redemption."
Jude 1:24. "Now to him who is able to keep you from stumbling and to present you blameless before the presence of his glory with great joy".
In Christ, God counts no sin against us. In Christ, we have clean hearts and right spirits. In Christ, we will never be cast away. In Christ, His Spirit will remain with us forever. In Christ, we will be upheld forever and ever.
When we sin, we never lose these things, but we may lose a feeling of assurance of them. But as soon as we confess our sins to God, He immediately forgives us and cleanses us (1 John 1:9), and we once again have the joy of His salvation. Praise be to God for His mercy toward us in Christ!