This is quite an interesting question and I think the answers you’ll get will depend on who you ask. Just to use an English example: Is the word “up” the same or different in the following phrases? Use up, tie up, finish up, give up, go up, upgrade, up end, end up. Some people may say it’s all the same and some may even say they’re all different. So in terms of words you already know being used again I’d say it’s personal feeling.
I terms of flat out new words there are probably a few (如何、如し、etc). They’re normally older or more formal versions of things you’ve seen before.
It is true that N1 stuff is generally much easier to remember, if you’re at that level and especially if you read, however I often see people say that this makes the higher level grammar “easier”. In my personal opinion this isn’t true since at N1 the thing you need to know is in what exact context to use certain phrases. Collocations and context become far more important at that level. This is the actual difficult part of N1 material, not remembering the words themselves. A big caveat is that if you never plan on taking the JLPT and if you don’t plan to go beyond casual everyday conversation for output then you can kind of ignore these nuances to a certain extent (not entirely) and just get enough of a grasp to comprehend the stuff when it comes up in media.
As for N2, I’d say it is vastly made up of everyday grammar still (a large chunk of N1 is also everyday stuff but not to the same extent). Mostly it is offering different fairly common ways to say the same things you’ve already seen. The contextual nuances are not as pronounced as they are for the N1 synonymous phrases and most the phrases have a broader set of contexts in which they’re used. N2 grammar is still very much “synonym hell” in the same way N3 generally is. It was for me anyway.
So I guess in conclusion my not so useful opinion is “it depends on the person”. As for practical advice, I used to go through the Bunpro grammar list periodically and bookmark any items I had seen before or that looked learnable with low resistance and then when I was ready to learn a new item I’d manually add them from my bookmarks list. This only works if you aren’t “learning ahead”, so to speak. You could also do the opposite and bookmark anything that looks totally incomprehensible and learn that first.