No don't worry you don't need it as both who have already passed graduation and the ones graduating can apply. So while filling the form they would ask you the same whether you have already graduated or that you are graduating, so over there you can mention the same. But you would need the graduation certificate during the admission which would come till the results of DULLB.

Hello Shivani,

Yes as you are in your final year of graduation this will be the perfect time for applying for 3year law course (LLB). DULLB ( Delhi University LLB) entrace exam is tentitively held aroun june and so the form must be out now for you to fill. You can give the entrance now and till the results come you would have your graduation certificate too which you would be required to give at time of entrance. 

This is the official website where you can get further details.

http://lawfaculty.du.ac.in/

All the Best!