Quite a few options actually, depending on what you want.
WaniKani native feature: Extra Study
This allows you to review burnt items. Downside: the list is everything you’ve already burnt, which, at level 60, is probably substantial. You have no control over which items pop up, although they are reviewed back-to-back (meaning/reading in random order), so you can quit and resume whenever you like. There are scripts that give you a bit more control what to review (and in what order).
Scripts: Self Study Quiz + Item Inspector
Item Inspector allows you to make a selection of WK items (per level, per stage, per… whatever really) and Self Study Quiz is then a practice review round on those items. Takes a little bit to get the hang of, but it’s a popular script with plenty of support on the forum
Script: Burn Manager
as mentioned above, with Burn Manager you can unburn stuff level by level and go through it, reburning what you already know. I do happen to have a variant of this script locally running that also allows reburning in bulk, based on item stage - that allows you to unburn all kanji from level X, do a review round on them, and then reburn all of them that made it to App 2, leaving you with only the stuff you failed in App I. If you decide to go this route and are interested, I could publish it (it’s not as fancy as Burn Manager though).
Scripts: Reorder Omega
As you mention you have open reviews already, something like Reorder Omega would be useful to do only certain reviews, unless you plan on getting rid of your current review pile first.
One option that I think hasn’t been mentioned yet, which doesn’t require any scripts, is to basically do a kind of a ‘manual’ reset. I have been using this technique (actually, two related techniques) for about half a year now, and I find it works just fine for me, and is even enjoyable (speaking for myself, anyway)!
I wrote up the two techniques in a comment to another post, which describes the whole thing from motivation right down to how to quickly zip through resurrecting several items using WK’s built-in features. If you just want the nuts and bolts, skip ahead to the “How To” section of the comment:
It’s possible/likely that there are scripts (such as those already mentioned) that can facilitate this basic idea easier than the manual techniques I describe. Personally, I just prefer not to have to install extra scripts, so I just found a way to do it by hand, but whatever works for ya!