Ronak, you should have completed your 12th atleast by the time of counselling. If you have failed your Board exams now but your betterment exams are atleast before July 26th, then you can appear for NET because then you will fall under the Category of those Students who are appearing for their 12th exams. But in case your betterment exams are after July 26th and even after August, then you unfortunately cannot appear for NEET