Hi

Is it RT or compartment?

You can never fail in an improvement exam. The sole purpose of improvement exams is to give you an opportunity to improve your scores but if you couldn't improve your scores meaning it is lower than your previous scores then it will not be considered. You can choose to repeat the papers if you want next year as a private candidate but it's a choice. CBSE has no say in this. You are still a passed candidate if your previous result is all clear and the same marksheet can be used for future admissions but if you still want to improve you can appear for the exams next year.

Hope this answers your query!