Hello Mayank,
If you have passed 12th from CBSE or any other board,why do you want to re-appear in that exam? 67% in 12th is not very low percentage, Though marks alone should not determine your future career.
Theoretically, yes you can reappear for 12th exams either in the same or different board and improve your percentage. You can also consider enrolling in a degree course of your choice and repeating 12th Std from NIOS if improving your percentage is the only criterion.But Serious advise will be to take admission in any Graduate college available and work hard and do your best at the Graduate level.