For macOS 10.15 and later only. This script will "refresh" the selected user-created Smart Playlists by removing the tracks they contain (if possible*) which obliges them to dynamically repopulate, ostensibly with different tracks.
*Note that tracks cannot be removed from a Smart Playlist which already contains every track of the library meeting its criteria--it would just repopulate with the same tracks. Smart Playlists with the "Limit to" and "Live updating" criteria in use are more likely to be "refreshable".
- Additional accommodations for macOS 11 Big Sur