CBSE students who failed in class 12th have to re-attempt the class 12th either in the improvement examination category or as a private student. If you have not failed in practical then you don't have to appear for the examination, the previous marks will be carried forward.

To know more about CBSE 12th, visit the link below:

https://school.careers360.com/exams/cbse-class-12th

I hope this answer helps. All the very best for your future endeavors!