Hello aspirant, 

It would be more helpful to provide you with appropriate details if you have mentioned details regarding the examination for which you want to have betterment exam. 

Hope you understood. 

All the very best!! 

Hey !

If by online betterment exam , you mean to say the CBSE improvement exams. Then , j would like to te you that the CBSE  improvement exams are not conducted next year. They are conducted in the same year , i.e. three months after the release of results. But i can not tell you the exact dates because the dates are different for different exams and different classes. So , kindly mention the class in which you want to give improvement.

If this is not the thing you meant by betterment exam , then kindly mention your query clearly in comments.