You may know your raw LNAT score but remember that those Unis may also have read and scored your essay - and read your Personal Statement - as part of their assessment. This could have been what let you down. Have you asked for feedback?
You do not have to make a big decision about this now - you could Firm Exeter, and then sit tight until Results Day. Depending on your results, you can then make a more rational decision about if it is worth reapplying, if you need to resit A levels, or if you should just go to Exeter.
If you do reapply, my advice would be to spread the risk far wider than you did this year. Oxford, Durham, KCL, LSE (and include the likes of Bristol, Warwick, and UCL) are all risky choices even if you meet or exceed the basic entry requirements, simply because of the thousands of applications each receives. And remember that you would have to retake LNAT next year if you do reapply - and you may not get the same score.