One possible plan:
Invoke vacation mode to temporarily prevent more and more reviews from piling up (and to stop new lessons from coming up)..
Then use an app such as Kakehashi (iOS and beta for Android) that uses your WK API key to sync the kanji that you have learned (supposedly) with the kanji presented in the app. I am not doing reviews in the app, rather I am taking kanji quizzes in the app, which I am finding to be an excellent way to refresh my memory.
I would not suggest resetting to a lower level.
Once you’ve adequately refreshed your memory, take WK out of vacation mode, and try to do 200 reviews at a sitting, and no new lessons, until you have knocked down your reviews to zero or to a manageable number.
See here, for example: