Hi,

NATA papers are checked by some of the best teachers and it will be highly unlikely that there will be a correction mistake, all the drawings are checked with accurate precision and the chance for increasing of marks is very low. Although you can count on your marks increasing because sometimes some teachers give the studnets marks so that he/she can pass the exam. 

So I wish you best of luck

Thank You

Hello,
It depends on the way you gave the exam. In general, the marks don't change even if you apply for revaluation. If you strongly believe, you deserve more, then there might be chances for the marks to change. 
Good Luck!