Jet has a lounge they should be able to give you access to - for the EXP status.

It is on the 1st floor or somewhere like that however - checkin, go out past the security barrier and climb the stairs to your left. Inconvenient.

There's a paid lounge (and also the lounge for kingfisher) called the BICA lounge that's not bad at all .. you could stop in there by paying some amount .. if you really need a lounge when flying domestic. I'd suggest that you arrive an hour or a bit less before your flight and just go straight through security after checkin.