Firstly, if you haven’t been able to get into Lovely Professional University, don’t get discouraged. Getting into IIMs is also a privilege. You can land decent jobs even as an IIM graduate. So just settle for the best IIM and achieve your goals.
But if you still think with one more chance you can ace the entrance exam of LPU, then take a dropout year and prepare well for it. It will be a year full of struggles but you will have to deal with it with the right spirit. Who knows you might actually get into LPA this time and fulfill your dream.