The Refresh button at the bottom of all Browsers is indicated by a circular arrow and is most commonly used when making manual changes (for example, when adding third-party banks/libraries) to your STEAM library, either in Finder or File Explorer. 

It can be found along the bottom of the Patch Browser, Multi Browser and Soundsource Browser. 

Note: For more information about how to locate the various Browsers in your Spectrasonics Instrument, see this article.