no, you cannot according to the admission eligibility

one must have secured a minimum of aggregate 75% in maths physics and chemistry in class 10+2 exam.

If a candidate has taken more than one attempt in 12th class or its equivalent, only his latest performance is considered, provided this attempt has been for the full component of subjects/courses prescribed. Students who have passed the 12th examination in 2016 or earlier are NOT eligible to appear in BITSAT-2018. Students who are presently studying in BITS at any of its campuses are not eligible to appear in BITSAT-2018.

http://www.bitsadmission.com/Eligibility_Criteria.aspx

the above link is of the official website you can check the criteria and assure it.

all the best!!