I strongly suggest reading the mnemonics for every kanji and radical. It does take extra time, but even with reviewing kanji from multiple levels ago I still remember some of their mnemonics if I’m struggling with it. For items such as vocabulary, I tend to skip the mnemonics if it’s a jukugo word and/or the meaning makes sense based off of the combination of kanji.
My process for remembering tricky kanji is to remember the story from it. Sometimes it’s a lot harder, but if you know your radicals then you can try to make up your own story to fit it into a batter context for yourself.
Now I know you said you’re crunched for time, so the best way to help yourself whittle your list down is to do 5-10 lessons at a time. You’ll slowly introduce new items into your review queue, and I would hope that helps make the process less overwhelming.
Good luck getting back into it! I hope to see you up to level 10 in the next few months 



