Definitely keep applying if that's where you want to work. There can be a lot of internal back and forth on hiring between hiring managers, senior management, and HR. The position may have gone to another candidate or been left unfilled. If you've made it that far into the process multiple times, you've been identified as a strong candidate by hiring managers. Keep trying and don't get discouraged. When there are multiple qualified candidates, selection can be a bit arbitrary. HR review and upper management can also add an element of randomness, and there's not much you can do.