I've never played as high as 25nl so take this advice with a grain of salt.

I think one of the most important things you can work on when moving up is 3/4/5betting. It's something that happens more and more and you need to have a standard plan in place to deal with it and exploit people doing it. There's loads of stuff about on this so just have a look through it and do some serious studying and looking at related hands.

I also think you need to be questioning yourself more and justifying your decisions better. Obviously this is something that takes time and your thought process improves as you study more because you gain a better "poker brain". I also think you need to be more aware of your own range in some situations this ties into the above though, or should do.