hello, here are the details of the age limit in neet ,

note that their is no limit in attempts in neet 

i. He/she has completed age of 17 years at the time of admission or will complete that age on or before 31st December of the year of his/her admission to the 1st year MBBS/BDS Course.  

ii. The upper age limit for NEET (UG) is 25 years as on the date of examination with relaxation of 5 years for the candidates belonging to SC/ST/OBC category and persons entitled for reservation 

You may appear for NEET as many time as You want To be Provided that You satisfy the other eligibility criterion including the Upper age Limit which is 25 years for candidate belongs to an Unreserved category and 30 Years for a candidate belongs to a reserved category, Check the link below for more details.

https://medicine.careers360.com/articles/neet-number-of-attempts-and-age-limit