Will she have an actual office at this new location in Chicago with staff, or are you talking about a virtual address rented for the purpose of making Google think you have an office at that location?
If your answer is the second one, then let me stop you there. This type of virtual address goes against Google's policies and can have negative consequences. See https://support.google.com/business/answer/3038177?hl=en for Google's guidelines. They've been going after these types of virtual offices for a while now. See also http://www.localsearchforum.com/help-support-google-local/978-virtual-offices-home-address-google-plus-local.html.
Leave the real address and focus on building organic traffic for Chicago. If she really wants to grow to a national level, you'll have to work on growing the brand to a national level through social media and content marketing. Unfortunately, there are no SEO quick fixes in this situation.