Must Christ go up again upon that cross? This is the only way sin is forgiven, by the shedding of blood. Without the shedding of blood there is no remission. How then does sin confession forgive sin, if no blood shed is made? It is Christ, and Him alone that grants us our forgiveness. His blood is sufficient, or he would've suffered since the foundation of the world it says in Hebrews (since He is the very sacrifice for our sin). We have forgiveness, it is not something we seek.
Ephesians 4:32 King James Version (KJV)
32 And be ye kind one to another, tenderhearted, forgiving one another, even as God for Christ's sake hath forgiven you.
If our forgiveness of sin is dependent upon our sin confession to God for the sake of forgiveness, who truly has saved us? Are we not saved by grace through faith? Then what error we have made to declare sin confession the means by which salvation is retained. A work of our owning doing, not Christ and Him crucified.