Greetings!

Yes you can in the following ways:

1. a private cbse candidate study from home and just go to write exam and perform practical. But as you have given 12th earlier your practical mark will be carried forward as private candidate .
2. National institute of open schooling is same board like cbse and icse, all reputed colleges like iit and nit and all over the world its considered equivalent as cbse. You can wait for exam for the next year or you can give on demand examination same year.

I hope this was helpful. Thank you!