If you re-register as a private student to take the Class 12 board exams again, the practical exam requirements are based on the regulations of the examination board. In most cases, if you have already done and passed the practical exams in the first attempt, you might not be required to do them again, subject to:

1. You having proper records of your earlier practical exams (e.g., mark sheets or certificates).
2. The board permits candidates who failed only the theory exams to be allowed to keep their practical exam marks.
3. You adhere to the particular rules of the board you are registered with (e.g., CBSE, BOSSE, etc.).

It's best to check this with the concerned board or examination authority to clear confusion and to ensure that you're adhering to their precise requirements. You can approach them directly for clarification regarding your case.

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