Dear Brizite,
Thanks for your post and congratulations on the promotion!
As to your question, I think that in most cases it would make sense to update the adcom with regards to this change (with some caveats - see below). The standard way to do so would be by emailing or faxing the admissions team a short business letter that explains the update and briefly indicates your new responsibilities, while thanking them for adding the information to your file, etc. Be sure to include any relevant info (SSN, online application account user ID, etc) so that they can promptly match the update with your file.
As to the caveats I mentioned above, there are several. First, I'd need to know which schools you applied to - as some actually have strict policies against supplemental updates (or limit them to when you interview, etc) whereas others are more open to communication. Similarly, I'd want to know where you are in the admissions cycle with each program (have you been invited to interview, and if so did you already inform your interviewer of this promotion?). Finally, I'd ideally need to know more about your background and how 'material' this change really is when it comes to your candidacy. It only makes sense to ask for the admissions team's time if you have something significant to share.
I know that this response is 100% clear, but that's the best advice I can offer given the details you have provided.
Best of luck,
Graham
