Okay, here is a GREAT truth!!!
Jesus Christ personally PAID for all sin, for all time, when He suffered and died on the cross.
He died in place of every sinner that has ever lived or ever will be born.
That payment however is not applied to a person until they want it, and accept it as a gift from God.
If Christ's payment for their sin is neglected/put off/rejected, then that sinner will at death have to pay for their own sins for all eternity in the lake of fire.
But, when a person repents and believes with all their heart that Jesus Christ took their place in suffering and death, and accepts the free gift that God now offers all peple - the free gift of the forgiveness of their sins - they no longer have to PAY for ANY of their sins, past present or future! Because it was completely paid for on the cross! God trukly has cast all our sins behind His back, and forgets them!
BUT there's more to learn! Because every believer still sins (and we all do), we will still experience the following:
1. We will Reap the life-consequences of our sins (like lung cancer due to smoking, or shorter lifespan for being a rebel against your parents, etc) (Galatians 6:7,8). You CANNOT reap hell for your sins now that you are saved, but you WILL reap troubles for your sins.
2. We will Get corrected/chastened by God, to push us back into line with the life of Christ (Hebrews 12:5-10) which is profitable to us, not punishment.
3. And we will lose rewards in heaven because of our stubbornness and love of sin instead of righteousness. As Christians, we earn rewards in heaven for our labours, and we lose rewards based on our laziness and unfaithfulness towards God.
So, in summary: At no point will any believer ever have to PAY for ANY their sins once they have been born again. THAT payment was made in full on the cross by Christ, the Son of God. BUT, we Christians will experience chastening, reaping, and the lose of rewards in heaven for every sin we may still be committing. And those consequences are good for us to experience so that we stay right with God and take Him seriously all the days of our lives! If there were NO consequences for our sins as children of God, we would only be spoiled brats, and God would NOT be a good Father!
As far as asking for forgiveness for when we sin, It is NOT to be saved or forgiven from the punishment of our sins again. There is no more means to forgive you anymore. Jesus Christ took care of it all!
Asking for God's forgiveness when we Christians sin (1John 1:8,9) is for two purposes:
1. So that our heart gets right / broken about our continuous giving in to temptation. To confess our sin is to own up to it / admit to it and take responsibility for it. Me confessing to God is me humbling myself and not trying to hide my sin, but come clean and get right with all my heart!
2. So that God doesn't have to bring up my disobedience in heaven that would require me to have to publically give God an "answer for it" at the judgment seat of Christ!