Hey, I am sorry but giving the exam after a gap is not allowed according to the board.

The guidelines of the board clearly mention it in the following,

• Improvement exams are for students who have passed but are not satisfied with their marks and are willing to take the exams again.
• CBSE Improvement Exam can be taken in one or more subjects in the succeeding year only after passing the subject in Class XII.
• The examination would take place in the following year.
• A candidate cannot appear for improvement examination in the subjects which he/she failed to pass.
• For improvement examination, only one chance in the succeeding year is permitted.

I hope this helped.

Best wishes