Hello student the eligibility criteria for jee main is either you've to be in top 20 percentile of your respective board or you need minimum of 75 percent marks aggregate as eligibility criteria says - Candidates must passed or appearing class 12 with physics chemistry and mathematics with minimum 75 percent marks aggregate from a recognized board.

If you appear in improvement examination for 2 subjects and you're clearing the cut off 75 percent then there's no need to be in top 20 percentile.

Feel free to comment if you have any doubt

Good luck