Unfortunately, no, if you want to do that, you have to reset the level. But! 700 reviews is a pile that’s more than possible to come back from.
Just don’t do any more lessons until you get through the review pile to avoid adding more, and start chipping away at the pile. You DON’T want to do them all at once, however, because otherwise this will come back to haunt you in regular intervals as part of the SRS system.
What you should do is when you have time, just sit down and do a few reviews here and there, spread throughout the day, in similar batches to when you were keeping up with it (so if you were doing 50 reviews a session on average, do 50 reviews at a time that works best for you). If you were doing 100 reviews a day, just pick two separate times during a day and do 50, or 4 separate times and do 25. What’s important is that it’s in a normal interval.
If your accuracy is good, then you will be out of this in no time! Just remember to not do ANY new lessons until you have the reviews under control. After you have the reviews down to a manageable level per day, then you can start new lessons again.
If your accuracy is suffering a bit, then that’s the time when you should probably consider resetting. I know that can be a bit demoralizing, but the important thing to remember is that in the long-term, it could help you learn more effectively, which is the entire purpose, right?
For future, if you ever need to take a break for a week or two, you can put WaniKani into vacation mode, which essentially pauses the system exactly where you leave it, and you won’t come back to a pile of reviews.
がんばってね!