I deal with leeches using a couple different methods.
The most important thing is recognition. Knowing which kanji are giving you the most trouble and identifying them as troublesome is often times half the battle. It forces you to stop and consider the kanji and think about the source of your confusion. This doesn’t always cure the leech, but in order to fix a problem, first you need to know that you have one.
I use a leech trainer user script to help me get extra exposure to leeches. This script creates a “mini review” that focuses on my worst items so I can pound them into my head. Some leeches will still cling after a few times through the leech trainer, but most of them drop off pretty quick after I give them a little extra attention.
For the ones that still stick around, I set aside some special study time in meat space - writing the character out by hand. Comparing it to similar looking kanji. Looking it up in kanji dictionaries. Reading practice sentences containing the word using Context.Reverso.net … Whatever I can think of to give myself a better grip on that kanji. If my original mnemonic isn’t working for me, I’ll come up with a new one.
Lastly, if I have a leech that refuses to die and it isn’t a common word … I use ignore script to kick it into a later SRS group and move on to other things, because I’m wasting my time.