If you are promoted to the next academic year, then you can't repeat 11th but you can delay your appearing year of 10+2 in the WBCHSE board.

There are no such repeating case but its case specific and I would recommend you if you wish to do so, then contact your school authorities for the detailed way to do so.

To know more about the WBCHSE, visit the link below:

https://school.careers360.com/exams/west-bengal-12th

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