You probably know that there is no need to change the date (or even show it in fact). In theory the date should be the date the work was created.
However I know people want to do this and the only way would be code. There's no built in way I know of. Code could open all presentations and update them once a year or probably more useful in the long run update the date when the presentation is opened if the year is not current. The latter approach would require a small addin to be created.
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