No. You can't write the improvement exam the same year. The forms for improvement exams are released around September or October on the official website. Candidates are supposed to write the exams in the next year, with the fresh batch of students, in the month of March/April.
Good luck.

No sir, you can not give your improvement exam in the same year. For this, you need to fill in the improvement form for the succeeding year (2020) and appear for your exam along with other students of class 12.

Hope you got your answer. All the best for all your endeavours!

Unfortunately, you can not appear for improvement exam of class 12 in the same year.You can only appear in the next successive year.
Good luck.