According to the JLPT Chart at wkstats, in order to cover all of JLPT N2 kanji by using WaniKani alone, you would have to get up to level 51 by your deadline. [ETA: Important caveats below in comment by @pm215 : The mysteries of Wanikani speed - #20 by pm215]
So, first off, you need to consider if getting to level 51 by your deadline (using WK alone) is a) even possible at all with WK’s gated levelling system, b) idealistically possible, assuming you had unlimited time & energy, but maybe not perfect accuracy, c) realistically possible, assuming more realistic limits on your time & energy.
Even if a) and b) are possible, you need to also consider c). Given that you’re saying you want to get to N2 ‘in the next year’, and assuming that means ‘within 365 days’, then I’m guessing that technically a) and b) are possible, but I would strongly suggest that you consider how much stress and pressure you’d be putting on yourself when considering if c) is possible.
If you have a hard date for JLPT N2, and that is your primary goal, then I would suggest that – while WK may be a good, strong, baseline learning tool – you may want to consider supplementing it with a more customizable tool which you can use to specifically focus on drilling JLPT Kanji more directly and (perhaps) ‘efficiently’. At least ‘efficient’ in the sense of drilling for a specific JLPT test date.
There’s the tried-and-true Anki, which is very customizable, and certainly has plenty of JLPT-specific decks to choose from, so you could kind of ‘default’ to trying that out. It’s free, too, AFAI-can-recall. And the latest version has a new SRS system that is supposedly more efficient, too.
But there are also other more-WK-like systems, focused specifically on learning Japanese/Kanji, which I’m sure other folks here will know more about than I do. At least one of those will be customizable enough, but also user-friendly enough, that it would be competitive with both WK and Anki as a best-choice for cramming for JLPT N2 kanji.
As for if you need to work on JLPT grammar, then the best choice, IMHO, aside from direct study (like with a textbook or course or whatever), for SRS, is Bunpro. It is particularly good for grammar (hence the name, a play on words with 文法), but it also has a new Vocab system, still in Beta, but getting better and better all the time, which also has Vocab Decks specifically for JLPT levels.
Depending on what you mean by “studied Japanese for many years”, then maybe getting to JLPT N2 would actually be very achievable. I would say that if you were starting from scratch (such as I was), then getting to N2 within a year would be super difficult and/or stressful/draining.
Heck, if you’re experienced enough already, then maybe even WK, with its gated levels, would even be enough. You could just focus on the Kanji and pick and choose which Vocabs you want to add in for the purposes of reinforcing those Kanji you find more tricky to remember. (You could use the Advanced Lesson Picker to accomplish that with ease, I’d imagine.) That might work!
Good luck!
I was a bit lazy with my lessons until about level 13 and thus had to do 80 lessons within 24 hours shortly before leveling up lol, but according to my heatmap, I did about 26 to 27 lessons every day on average.
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