Hello Sejal, the eligibility for NEET/AIIMS is just a minimum aggregate of 50% for UR, 40% for SC/ST and 45% for PWD in class 12 boards with PCB/biotech and english as compulsory subjects.

https://medicine.careers360.com/articles/neet-eligibility-criteria

With 68% you have very well cleared the eligibility for the NEET and AIIMS exam, and since it is the field you want to pursue, its totally okay if you prepare for that with focus of reattempting the 12th boards.