You would need to open the files, refresh, then save. If they are opened by another user then this would not work.

When dealing with SharePoint I usually will map a network drive to the SharePoint folder. So for example if I map X:\ to the SharePoint folder then I could open the workbook like I normally would in a Windows folder.

[VBA]
Set Wkb = Workbooks.Open(Filename:="C:\SubFolder\Filename.xlsm")
[/VBA]

Depending on the data you want to refresh the following might work:

[VBA]
Wkb.RefreshAll
[/VBA]