If a child is playing in a mud puddle, their parents do not clean them off and tell them to go back to play in the mud again! Once God cleanses you from all unrighteousness (1 John 1:9), He tells you to go and sin no more (John 8:11). Jesus would not have said it if it was not possible. Once you know the way of righteousness, you are expected to walk the way of righteousness (2 Peter 2:20-22) not waver back and forth from righteousness to unrighteousness.