Hello aspirant,

Yes you can take a drop for a year to get IIT Bombay. But before taking the drop you have to honest with you that will you really qualify for that college. There are too many student who take drop for a year some will qualify and some don't. But if you gave this year jee then you will also predict your upcoming opportunity to get that college. If you score too good this year then obviously you have to go for the drop but if you don't have good score then it will not good to take the drop. As you can see there are too many students are fighting for some seats so the competition are bit higher, but if you believe in your self that you can easily clear it then you have to do it. But be honest with yourself, the your limits and the circumstances and consciences. 

Hope this is helpful. 

Best of luck for your future and go head to achieve your goals of life.