A percentile is the no.of Candidates who scored better than you in the exam. Going by that, to calculate your JEE percentille, we should use the formula 100 - your total percentile score. Now 869010 Candidates appeared for Jan exam. Going by that, the rank formula  is (100 - your total score) X 869010 /100. The rank can be predicted by using the formula, (100-your total percentile)*869010/100. In your case, your daughter's approximate rank would be 508283. Let's say the number of candidates for April exam increased to 12,00,000 then your daughter's final rank shall be (100 - your total score) X 12,00,000/100

At this point in time, it is difficult to predict the JEE Advanced qualifying marks but 85 percentile and above should be an ideal score. With 41.51 even with OBC reservation it is difficult. So she has to appear for JEE April session.