Hi

According to sources

In UP board- candidate can give class 12 th exam again(same board) for improvement in score via improvement form only. But in case you have passed your class 12th already from UP board then it is not advised to give class 12th exam from same board again.

Kindly check it with your school adminstration for credibility of this rule in Uttar Pradesh

If it is so, you can still give class 12th from any other board or NIOS (National institute of open schooling)

Best of luck