If you have prepared hard for atleast six months before the exam, then just revise all the chapters and try to solve atleast one question paper per day. If you don’t know any concept in that question paper then try to learn that; thereby you can be thorough in subjects and your confidence level also will improve a lot.
If you have not completed your basic study in the last six months before exam, then don’t worry about the current exam, take the books and start studying, so that you can appear for next year NEET exam.