Updating excel links
There are many options in Excel that control this depending on the kind of link it is.
It is likely that the data used to create the graph is coming from an Excel worksheet, so why not link the graph on the slide directly to the Excel data. I will describe each method, and then show a table that summarizes the differences.
With both methods, you must be careful of who has access to the source Excel file from the Power Point slide.
Anyone who can access the Excel file can see all the tabs and data, including any confidential information.
In Power Point 2010 and above, in the Info section of the File ribbon, there is a button to Edit Links to Files.
You can select the links and click the button to break the links.