You are unable to meet the required percentage in the 2025 JAC improvement exam, you cannot apply again for improvement through the JAC board.
also you cannot give private as this is for repeating exams not for improving scores.
Your best option is to take your Class 12 exams through NIOS its a government recognized board for private candidate to improve marks, and the result is valid for competitive exams like JEE.
Hope it helps..
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