Do not let one bad exam ruin the rest. Make the habit of thinking about the one that is coming instead of the one that passed. Meditation will help you do this.

Continue your monchobi till the results are announced. Spend these days for good cause with good company. Pray and give to charity regularly.

This is very important that you learn from mistakes. If your results are not satisfactory, do not blame luck or the teacher/authorities, take responsibility for your own grades. Find out what you are doing wrong and avoid making the same mistake in the future.