Dear Aspirant

Hope you are doing well

Now let me go through your question

Yes, you can pursue your 12th class from NIOS again. NIOS stands for National Institute of Open School. Eligibility criteria for pursuing 12th from NIOS : Candidates must have complete his/her 10th class from recognised board.

And  there is no upper age limit

If you want to know more about it check out the link given in below https://www.google.com/amp/s/school.careers360.com/exams/nios-class-12/amp