Hey Neha,

You have to inform to the clerk of your school who registered you for isc exams.

He will explain everything in detail(exact details).

But as far as i know, the fee for improvement exam is 1500 INR for 6 subjects

You would appear as a private candiate and not as a regular candidate.

You have to give the practical exams, don't get confused whether you have to give practicals or not.

Make sure you be in contact with a regular student and get updated with new information about the exam.

All the best!