Should I drop one year for the preparation of JEE 2018? My JEE Mains 2017 cut-off score is 45 and I belong to general category.

Yes, you should drop one year if you want to do engineering only. Well your score is low. You need to work hard. Good luck.

See, there is no chance for you to get any NIT, if you want to do hard work on your studies and if you have enough confidence to clear next JEE then you should go for next JEE, otherwise, you can get any private college like SRM, VIT, BITS-Pilani, UPES, LPU or COMEDK exams. Good luck.

Yes, you should. I am also dropping a year for the preparation of JEE mains 2018.

You can do so if you are willing to work hard.