Hello student yes you can appear in improvement examination to increase your aggregate percentage and make yourself eligible to get admission in NIT's and IIT's.

This year MHRD minister scrapped the minimum 75 percent marks for admission for IIT's and seats through CSAB. So if you've cleared the cut off you can appear in Jee advance and get admission into IIT on the basis of passing certificate only.

Use careers360 college predictor - https://engineering.careers360.com/jee-main-college-predictor?icn=QnA&ici=qna_answer

Feel free to comment if you've any doubt

Good luck