Hii Ahara... You can give JEE Advanced 2 times ..

But after 12th if you drop a year for the preparation you can give the exam only once.

for ex. - If you gave your 12th board exams in 2014 ,and drop a year you can give jee advanced in 2016 only. No second chance !!

If you gave your 12th board exams in 2014,give Jee advanced first time in 2015 ..you can attempt 2nd time in 2016 .

Hope this helps you. All the best.