No, you can't get a refund after 7th of JoSAA. You should have seen ‘Business Rules’ given in detail on official JoSAA website.

Let me give you some further insights:

1. A candidate, who has already accepted a seat allotted by JoSAA 2017, can withdraw the seat by reporting at a reporting center before the last round of seat allocation (i.e., if JoSAA conducts a total of seven rounds of seat allocation, candidates can withdraw up until during sixth round of seat acceptance period). There is no option of withdraw of an accepted/allotted seat after the announcement of last round of seat allocation.
2. Candidates who accept the allocated seat in any IIT by reporting at the admitting institute or a reporting center but do not withdraw seat, irrespective of whether they attend classes or not, become ineligible for JEE (Advanced) in subsequent years.

So, even if it was your first attempt but you accepted your seat at the reporting centre and didn't withdraw before 6th round, it is advisable to join your college otherwise you would be ineligible for your 2nd attempt for both JEE Mains and Advanced.

Hope it helps!!

Hello! You can  get refund if you withdraw your admission before the last round . This will help them to put your seat for counselling in the last round , hence the seat will not be wasted. If you withdraw your seat in the last round you will not get any refund.