Instead of preparing for the examination of class nine and ten again would mean wastage of two precious years. In your case, it would be better get your date of birth corrected with the concerned authorities. If you are born in a city hospital, you may ask them to provide a fresh date of birth certificate but in such cases, you need to know the date of admission of your mother relating to her delivery.
If born in a village, approach Gram Pradhan in this regard to help you and once you get this details, approach the SSC Board for the corrections of your date of birth. In this go through the remarks of your school headmaster in your application and your application should be accompanied by the requisite fees required for this purpose.