If you're using PI Datalink 2013 and later, you can configure PI Datalink to automatically refresh based on a time interval and also refresh type (calculate or full calculate).
thanks for your reply! That helped And I also found out that you can refresh the process values in Excel Data-Add-In with F9 on the keyboard.
There are 2 short cuts for the DataLink's update.
1 F9 (Calculate)
2 Ctrl+Alt+Shift+F9 (Full calculate)
The difference is that if you use PI time, for example *-8h, it requires Full calculate.
If there is only current values, F9 works fine.
If you open "Settings" in the PI DataLink ribbon, it allows to determine which calculate option does "Automatic update" use.