If you have done the payment, its a non refundable amount. So you don't get that back anyway.If the payment hasn't been done, then you may leave that form as it is. But they may have your data in their database. So there may be a chance your attempt is counted. If that's the case, then you may appear in the examination just to have the aroma of the JEE Thing.But keep in mind, FINGERS CROSSED if you have to attempt the paper as a dropper you might not be able to sit if there aee two attempts.If JEE allows three attempts then there's no harm in doing any of the above cases.