It depends on the course that you want to apply for. According to the official notice available at: https://cucetexam.in/CUCET2020/Document/Eligibility_Criteria_CUKER.pdf , the upper age limit for for UG courses is 19 years and PG courses is 25 years but there is relaxation for Reserved Categories. And there is no upper age limit for other courses. So depending on your age right now and the course that you are appearing for, you can appear for CUCET those many times until you turn 19 or 25. Please do help us with the course you are enquiring or please use the link given in the answer to check the age limit.