Hey
First of all since you have completed the cbse level i.e. NCERT level.. i think your concepts must be strong by now.
Though BITSAT and AIEEE mention that their syllabus is NCERT , dont just blindly follow it. You need to do much more than NCERT.
You need to test the concepts which you have mastered through solving ncert books by solving questions from some reference books.
I suggest you do the MTG explorerbooks for BITSAT..They are very good.
Maths....RD sharma,TMH, A das gupta(any one)
Physics...HC verma, or Resnick Halliday
Chemistry...OP agarwal,P Bahadur
I hope by solving the above you can maximise your score like anything.
Cheers!!!