As a high intermediate speaker, your job right now is to look for holes in your knowledge/skill sets. Some strategies:
1. At this point, you'll want to know the top 1000-2000 words. Grab a Routledge frequency dictionary of Spanish and go through it, looking for the words you don't know yet and adding those into your flashcards. While there will be example sentences in that dictionary, you'll learn more if you make your own example sentences with a tutor's help (as per https://fluent-forever.com/italki-tutor-guide/ ).
2. Take an honest look at WHERE you're going to use Spanish (casual conversation? academic? sports? food?), then look for vocab that seems high value in each of those categories and learn that stuff in the same way as #1, so you get better in each specialty.
3. For grammar, I find the best way to really address this is to write a lot. Write out content, have a native speaker correct it, and make flashcards for every correction. Make a habit of this. It should add a great deal of polish.
4. See if you can find a tutor who can do this live with your speaking (i.e., have a conversation, and every time you mess something up, they catch it, and provide a corrected way to say the thing you *wanted* to say.
5. For listening/reading polish, that's a matter of exposure and being aware of difficulty levels. Read and listen to a ton of content, aiming to understand around 85%. If you're understanding 95%, consider ramping up the difficulty until you're back at 85%.
I think that's all I have!