Ask HN: Best Resources for SaaS UX / UI Design

Hey folks, I run a small SaaS application that is 2 years old, it's doing okay and slowly growing BUT as time has gone by and we've added more and more features the interface has gotten a little.... messy. I'd love to be pointed into the direction of some recommended books, videos or blogs to read on how to get out of this and point me in the direciton of user experience.