Yes. You should update your file with any significant accomplishments right up until you get an appointment or LOA. If your GPA goes up with your first quarter grades, you should definitely update. Some students kind of vege out their senior year and their GPA goes down. By getting good (better) grades, you are showing your character which demonstrates that you are ready for the challenge of USMMA. Our DS updated his file in October of his senior year with an article about him from our home town newspaper. A few days later, he got a call from admissions saying they had pulled his file when they received the update and recognized he was "just the kind of fine young man we are looking for." The rest is history. You never know what will make a difference, so I would definitely err on the side of updating. At the very least, they will know you are still sincerely interested in an offer of admission.
