Hello Student

Yes you can change after you failed in RBSE Board in class 12 exam.  If you change it to a CBSE school then you have to take  admission in  class  11 of CBSE board school and after 1 year exam then you will be allowed for appearing in the class 12 again. But in my suggestion it will be better for you to continue your study in the same school on  for Rajasthan Board of secondary Education and try hard and do  follow a systematic routine of study, practice previous years question paper and minutely then you will get surely good result in 12th class of Rajasthan Board of secondary Education.

Hope this will help.