One possibility to consider is resetting to a previous level to wipe out the massive pile of haunting/leeching vocab/kanji and restart at a level where you still feel confident. I had a similar situation not too long ago and wrote a post describing how I decided to reset (or not, but in my case, I chose to): After a long absence, I reset (to level 7), and Iām glad I did
Something to consider: It might actually end up taking you less time to reset to a certain level and follow the WK levels in order again, than to try to wrestle with dozens or hundreds of items from different levels all kind of randomly floating around in your review backlog. Even better: It might make doing WK a lot more fun/enjoyable again! 
But not everyone will agree, so this is just a suggestion to consider the possibility. In the end, do whatās best for yourself, of course.