Check out this KB article method 4:
Enable the automatic update for data connections or workbook links in
the Trust Center To enable the automatic update for data connections
or workbook links in the External Content section of the Trust Center,
follow these steps:
Click the Microsoft Office Button, and then click Excel Options.
Click Trust Center.
Click Trust Center Settings.
Click External Content.
Click to select the following options, as appropriate for your situation:
Prompt user about Data Connections
Prompt user on automatic update for Workbook Links
Click OK to close the Trust Center dialog box.
Click OK to close the Excel Options dialog box.
You cannot and should not have objects or processes managed by the trust center automatically do anything. This is setting a bad precedent. Instead, you should set the workbooks to prompt the users to update every time they open the workbook. If the users are prompted, they will be reminded to update the links.
Additionally, you can take a look at this KB article