I’d suggest waiting a few weeks before sending a note. It may stand out a little more, and you can mention how you are still strongly interested and give a brief update of anything new. (At the least, that you will be sending in the midyear report soon.)
I’ve heard admissions reps say that one relatively short, strongly meant note can help. A long letter, or 2 or 3 notes, or sending in materials they didn’t ask for will not help, though it could annoy.