Go to France for a couple of weeks, come back and retake it - try and freestyle a bit more than you might have done, or at least pretend you haven't learnt the chunks of text. Look at the markscheme and find out what gets you the marks. Use loadsa vocab, tenses etc. Try and relax in the exam room, listen to the questions and answer them as opposed to answering anything that wasn't asked. Bring some water in if you want.. Also if your examiner is a teacher he/she might not know how to get you to show your full potential so you might wanna consider that as well