This may help. However, I believe if you are choosing Data>>Refresh, the data should update. You have not created an Extract, correct? I know you said you were using a Live connection, but just need to be sure.
Thanks for the fast answer, Matthew!
Unfortunately, it didn't help yet. I am sure to have no extract and I don't have the server, just the desktop version. I noticed that any data added to the data source is taken over into Tableau when refreshing. Row deleted or values set to null in the data source appear unchanged though after refreshing.
same problem here. Tableau Public 8.2 on Mac OS X 10.10. But I had the exact same problem with the trial version of Tableau Desktop for Mac, with OS X 10.9 and 10.8. There's NO WAY to refresh the data after an update of the Excel file. I Have to recreate the graphs from scratch every time! Very tedious.