As an update, it seems as though one part of the plant had a particularly bad infestation because the other parts are finally starting to put healthy new growth that isn't being killed by mites before it can develop.
Increasing the spraying frequency seems to have managed to (mostly) get them under control, though I'll probably prune away all and any damaged leaves regardless.
I also harvested my first Aji Limon pepper a day ago...though I can't say I was terribly fond of its flavor (It reminded me of lemongrass mixed with soap).