are you referring to the Visual Overview graphics on elements, services and views? Because these is no manual refresh option on those (similar to like a web page reload in a browser), but I was also wondering why you asked the questions as I can personally not think of a reason why one would need that. Because these graphical views should always update automatically (e.g. alarm color coding, real-time values that are displayed, etc.), and if the underlying design is changed (through edit with MS Visio) then also automatically all open sessions showing that graphic should automatically refresh.