Yes, you can repeat your class 12th if you are not satisfied with your score. If you want the class 12th and improve your score, you can follow few steps.

First you need to contact your school. You can get more consultation and they will guide you more about the process of repeating the class.

You need to get re- admitted to school.

Register for the MHSC board as a regular student.

Apply for exams and prepare well for the exams to improve your score.