Although my reviews never quite reached 1,000; they maxed out at around 975 or so. So I’d like to tell others who find themselves in this position that it’s really not as bad as it seems.
My reviews heatmap is below (grey=0, red=1-49, yellow=50-99, light green=100-149, dark green=150-199, blue=200+). I hit level 6 in October, and made it about 2/3 of the way to level 7 before I lost steam at the end of January. March and April make me laugh - you can see I logged in a few times, did a dozen reviews or so, and then said oh crap this is just a waste of time. Then I started my second semester Japanese night class in mid-May, and by June realized I needed to get serious about my kanji.
I decided to try and do at least 100 reviews a day, and never more than 250. My goal was to get to the point where I logged into WK in the morning and had <100 reviews waiting for me. That was today! As you can see from the heatmap, it only took me three weeks. The 3rd week was a little intense, as I had a lot of leeches piling up, and I wanted to get back to normal by the end of the 3rd week. So I did some 200+ days this past week.
So if you’re depressed about the huge number of reviews you’re facing, just dive back in. The first few days will be pretty miserable, because it seems like you’ve forgotten everything, but I was amazed at how quickly it all came back.