A couple of years back I had a number of offers,this years I have a number of rejects

I am preparing for a switch and I have 7 years of experience in product management. Can somebody please suggest me a way of preparing. Few interviews that I have given, rejected me because my case study solutions were not at par with my years of experience. Can somebody please guide me on how to prepare. Any material for preparation or mock interviews that I should be giving. If anybody has similar years of experience and wants to prepare together for good product companies, you can DM me. Looking forward for your help.