I am writing my update currently, and plan to include info about continued interest, extracurricular updates as well as grades. How long should it be? A page or less than that?
Definitely a page or less. Your goal is to communicate interest - in a sentence, and to update your file. So if you have won any awards or prizes, here’s the place to tell them.
You can update grades beyond Jan. But my counsel is that the best letter is one which makes you a stronger applicant than you were the first time they reviewed your file by adding to it, so avoid telling them anything they already know.
If you were not accepted anywhere else, it is okay to tell them that you were waitlisted at all your schools so are in a position to accept quickly should they make you an offer of admission. This is helpful for schools to know. Just remember that if you do get off the WL somewhere, you should remove yourself from other WL.
@gardenstategal thank you for the advice!
I am pulling for you, @Totorocinnamon03. (Your name makes me think of that gorgeous movie every time I see it!)