After a long - I would say years long - phase of mine where I continuously wrote cliched romances with fairly flat characters, I created a rule for myself - when beginning a new project, I focus on the negative.
It sounds like backward advice, and it probably won't work for anyone. But for me, it does work. What I'm suggesting is to take one thing - or several things - you're absolutely awful at, and make them essential to your story. You can't write fight scenes to save your life? Write in at least five. Awful at world-building? Write fantasy.
Personally, I'm always finding new weaknesses in my writing. But I'm also always seeing improvement, so long as I don't shy away from everything I am bad at. When I neglect this rule, I typically look back and find that my writing quality has stayed the same. Even a single short story in which you force yourself to write something you aren't great at can improve your writing a TON.
As a disclaimer, I'm not saying to get stuck in that trap where you can only see the negative aspects of your writing. That's all too easy to do, and focusing on the positive side is just as important. Think about what you're good at, but don't stick to comfort zones. Branch out and be as diverse as possible.
You probably won't thank yourself while writing, especially at first - but the improvement in your writing will be worth it in the end!
If you've read to the end here, feel free to let me know what you're greatest weakness and strengths are in your writing. My strong point is dialogue, but I'm still trying to improve my descriptions!