Hello Parth, according to the eligibilty criteria for BITSAT , you should have an aggregate of 75% in PCM and individually you should have 60% of marks in all the three subjects. So in my opinion , i think it depends mostly on you . If you think that you have really improved over the last 1 year and can really crack the exams irrespective of the eligibility thing and if you think that you have improved  enough to overcome the eligibility criteria , i think you should definitely go for BITSAT. Remember that sky is the limit . You can achieve anything if you are determined enough to achieve it .

All the best for your future endeavours and i hope you crack BITSAT 2019 . Good luck.