The exact way I was doing, every new sets of items / new levels, was repeating Self-Study mode with EN=>JP (because of no-Kanji hints), for a few times, until I get a good accuracy. I don’t even have to set up Anki. And it can be frustrating to see yourself not easily remembering what is required…
As a matter of fact, mnemonics may help, but not so much. It’s pretty common that I have to make up new (and another new) mnemonics, for initial remembering.
Kanji pronunciations? Jukugo? I don’t care about that, as it is just another vocabulary. Just make sure you remember the pronunciation initially somehow; and IMO, Kanji itself can also be a distraction. That’s why EN=>JP come into play. Kanji readings become more meaningful retrospectively, though.
As a matter of fact, I almost always remember vocabularies before Kanji.
As for repairing you backlog, common choices are either, reorder (but you don’t have to do it all at once), or reset.
I am not sure if caffeine improves learning and memory or not; but stimulants in general may improve attention in ADHD or the spectrum, which may in turn improve learning.
Nonetheless, I am sometimes afflicted by caffeine downtime, that is, some time after the dose.