I agree with medie. Just pretend you've already fixed it in the beginning and keep writing with how you want the characters to be now. If you think of scenes that could explain the shift in characterisations, you can always add them in later as you go (thus increasing your word count even further).

YOU CAN DO IT! *waves pompoms*

ALSO! Feel better! That sucks that you're unwell at the moment. *hugs*