How long should it take for iCloud Drive on Yosemite 10.10 to refresh and reflect changes made elsewhere?
According to this Apple iCloud Drive support page:


  I’m editing a document now. When will my changes upload to iCloud?
  
  When you'll see your changes depends on the app you're using. Pages,
  Numbers, and Keynote upload files to iCloud regularly to make sure you
  don’t lose any changes. 
  
  Other apps upload your files to iCloud only
  after you save them to the iCloud Drive folder. To see your saved
  files on a Mac, go to Finder &gt; iCloud Drive. On your iPhone, iPad, or
  iPod touch, go to the iCloud Drive app. On a PC with iCloud for
  Windows, go to File Explorer &gt; iCloud Drive. 
  
  If you still don't see
  the latest changes or you see an "in-progress change" icon or the
  iCloud Drive icon in the notification area (system tray), try to save
  a new document to the iCloud Drive folder. Then check the iCloud Drive
  folder to see if the changes appear.