It's totally depends on aim of student if he/she determined to get into top NITs then he/she can go for 3rd attempt otherwise, it is advisable to take admission in other colleges.

It is recommended to the students that they should take as many as entrance exam for engineering that is BITSAT, VIT, SRM, Manipal and Amrita as they are top private colleges and offer good placements. There are other good private college as well which consider JEE main marks in order to take admission.