If you are getting interviews then you are doing something right! Try to see each one not as a failure, but just that you weren't the best candidate for that school. There's most likely nothing wrong with what you're doing at interview (have you asked for feedback?) so you just need to keep trying until a school realises that you are the best candidate for them! Stay positive and don't let rejections get you down. I know it's hard not to take them personally, but try and make up a non-personal reason why they might not have chosen you (eg. "They were obviously looking for someone with more experience") to keep your spirits up. Good luck at your next interview!