You can top dress with worm casings which is essentially really black soil. Scrape off about a half inch of what you have and spread black dirt worm casings around the top. Not perfect but it can help.
I like this brand because I emailed a question and the owner responded - nice guy. And man it is some of the prettiest black dirt you ever saw (if black dirt can be pretty ) plus it does not smell. You can probably find it locally too. It is not a miracle but it can help. Supposedly spider mites hate being around it because they can sense there is dead stuff there aka worm casings.