Because Channels is basically guide-/episode-based, its recording engine relies upon the guide data given to it. The way it works, it won't re-record something it has already recorded, unless it has: 1) been deleted, and 2) been told to re-record deleted episodes by using the advanced editor for passes.
While Channels does have the ability to override its defaults, presently it only allows you to manually request a re-recording for an existing episode. There is presently no option to do as you want, because it expects the
guide data to accurate/correct. Also, since the guide data for Pluto is inferior—and ViacomCBS probably doesn't care, because this is their free platform—the situation is unlikely to change.