As far as I know, the only way to clear the texture map cache is to close Poser and re-open, as you said.

Hoping someone has a better answer.  

This could, perhaps, merely have said "bookmark"....

===========================sigline======================================================

Cage can be an opinionated jerk who posts without thinking.  He apologizes for this.  He's honestly not trying to be a turkeyhead.

Cage had some freebies, compatible with Poser 11 and below.  His Python scripts were saved at archive.org, along with the rest of the Morphography site, where they were hosted.