If you don't want the rewards that have been predestined for you, then you don't have to ask for forgiveness.
If you want to be further sanctified, then yes, you do need to return to God and confess sins to Him privately.
The life in Christ only begins with salvation. It doesn't end there.
The life that ends as a murderer, never having asked for forgiveness, ends in hell.
If you don't understand that, you're misguided at best.