Hello,
1. The las date for filing the retunr is 31st July for individuals
2.Yes you can a rebate on the interest paid towards your daughter education
3.Interest paid towards Education is allowed as deduction u//s 80E. So, you need to enter the interest paid details in the deductions U/S 80E
If you have already filed your returnand you want to make the changes , you have to file the revised return to claim deduction
With Regards!!!