The Fisher Building is going to get some more upgrades.The 1928 Albert Kahn masterpiece — often thought of as Detroit’s largest art object — has been undergoing some renovations but anyone who’s worked there knows there is more work to do. The refinancing from Boston-based UC Funds that retires existing debt will allow the ownership team of The Platform, HFZ Capital Partners and Rheal Capital Management to do four main things: modernize three more elevators, renovate the public bathrooms, create a conference center for the building and restoration of the brass doors and other artistic details.