I've never re-submitted something myself, but the two you submitted are so close that if someone didn't like the first, I doubt they'd like the second.
I think you (well, anyone really!) would need to make some drastic changes to see a significant change in score.
Like the others have said above, add a background, some animals, maybe even some makeup. 3nodding
First I'll say that your concept was creative- I see Disney princesses often but I don't recall Cinderella in her pink gown before. However, when I looked at the two entries via the arenas I did not notice a different between the two entries. It is only by having them next to each other and staring for about a minute that I noticed what you did. I can imagine others who saw the first one did not notice any alterations as most voters tend to quickly glance and vote.
Sadly, I don't have suggestions to offer with respect to improving the avatar, but I hope what I said provided some possible insight as to why you got the votes you did. Trojan.exe gave some great advice. Wait a few weeks before resubmitting so anyone who saw the previous ones might forget and they can look at it again fresh.