Hi Sanjay,

You can join crash courses for mock test series for preparing DU JAT  from Edumentor, Pratham they will give you proper guidance with important topics regarding the syllabus also will help you in solving the mock test or else you can also join online mock test from  supergrades, bullseyes  if you only want to practice the previous years paper. Also, you can refer arihant books also for self assistance.

I hope this will help you. Wish you good luck.