Wait a minute! Forgiven is everything. Once for all times.

By the which will we are sanctified through the offering of the body of Jesus Christ once for all. Hebrews 10:10

We cannot do anything that has something do to with our salvtion. The confessing is the condition for a holy life and it is for the relationship to the father. But repentence does not save you. Furthermore it says "confess" in 1. John. Satan mixes things up. It is so important to discern.

My little children, these things write I unto you, that ye sin not. And if any man sin, we have an advocate with the Father, Jesus Christ the righteous

1. John 2:1

The more interesting question is wether a real believer could do this. And have in mind: God judges saved persons with physical death because of certain reasons. When there witness is dead for example and they stopped to confess. A believer can fall into sin and he can do this:
And grieve not the holy Spirit of God, whereby ye are sealed unto the day of redemption.

Ephesians 4:30