Considering that you have reached more than a third of what Wanikani has to offer the strategy for keeping that knowledge “fresh” eventually will go hand by hand with using that vocab more often, as memory, even SRS assisted, it’s not enough (or fun either).
Reading more and more is something that helps a lot in this regard. You will see vocab in use lots of times before the due dates in a SRS, plus you will see similar words that add dots to connect related vocab in long term memory as well.
As @bnheise mentioned, Wanikani might not be the best place to review vocab (specially when you start to be able to DO things with what you’ve learnt). I needed more context (than kanji alone or the sample sentences they provide), so I came up with a routine to search for sentences using the words that Wanikani dropped with each new level but not in the vaccum of Wanikani but in my own shows. That helped a lot, specially when I wasn’t reading much, still does now, though reading adds much more to using vocab when it becomes something regular.
Anyway there’re great tools for vocab, some made by users of WK too. If you reached a point where kanji and grammar basics are covered, then it’s mostly vocab from here on. So it might worth to look for some specific routine for that … there’re some interesting book clubs in here as well.