I disagree with you that because we are saved by grace, not law, we are not asked to keep the law. Keeping the law never results in our salvation, but a saved person who has been freed of sin through grace is asked not to go back to that sin.
The fact is that we, being made of flesh, sin even though we do not want to sin as Paul tells us, but that fact has no bearing at all on that we are asked to repent of all sin.
Matt. 5:48 Be ye therefore perfect, even as your Father which is in heaven is perfect.
1 John 2:3
By this we can be sure that we have come to know Him: if we keep His commandments.