I think I might been drunk or something, posting what I did before. There's nothing wrong with going back and updating your previous work, but usually I prefer to redraw the entire thing using the same basic idea/concept. I feel working on the same drawing might lead to repeating the same mistakes..
Template88
You are too attached to your works if you feel this way. Each piece is just a step, it can be forward,nowhere or backward, it's up to you to decide what direction you go but each individual piece is unimportant. What might be important is the destination you choose.