Hello Ravinder,

You can still fill the form even if you are an improvement student. Generally the improvement exam and its result gets released in the same year that is, in your case in 2019 itself. This is what the DU guidelines say,

Yes, you can submit the online registration form by choosing “Awaited” in the drop-down menu of “Result Status” on “Academic Details” page/section while entering the information. However, you will have to fulfill the minimum eligibility criteria/meeting cut-off list of that course/college during the stipulated period.

So, instead of iving the passing year you choose the option of "Awaited" as your final result of improvement exam is not out yet.

Best Wishes!