Your application reflects different aspects of you and should be treated so. I don't think the school will reject you based on one score but if you can't demonstrate your English communication ability elsewhere, it'll be difficult for them to believe you will do well in an English speaking environment.
If so, then I think I can let it go and focus on essay and interview, which is a good way to demonstrate my English communication ability.
To be honest, compared with other aspects, speaking is really a weakness for me. So I have a long way to go, not only in interview, but in the real overseas life.
Re rescore, do you have any suggestion? It seems to take you the same opportunity to increase, maintain and decrease.