I lost all my AS biology notes !!!Watch
Failing that, there is no issue going through the material again and making new notes. It is a pain in the backside, but it does benefit you in the long run if you had forgotten some of the content anyway.
If your deadline is September, then I suggest writing a few notes every day, rather than trying to do it all at once. This will give you manageable tasks each day and still also allow you to focus on other things.
You can try using some PMT notes as well.