When your data source is ready click "Update Active Slide" to update the currently selected slide.
When clicking "Update Active Slide", the user must select the previously saved source. Now, the slide will update and import the data from the source.
For instance, if the user has typed "<<test>>" at the slide, and change the value in the source to "Heading", this process will import the data and thereby update the specific slide to "Heading" instead of "<<test>>".
Furthermore, the user is able to update all slides in the presentation with one click.