I've never heard about the possibility to refresh them - let's see if others can help.
I believe Photoshop scan all script during Photoshop start up build a list of script names for its menu Fils>Scripts>Script Name. That it also registes plug-in scripts and populates its about plug-in and script help info as Photoshop start up. I also link Photoshop Preset\Scripts folder to my photoshop script tree. So I do not think any new script names can be put into Photoshop menu File>Script>Script Names while Photoshop is UP. I edit Script in the list and test them all the time when Poptoshop is up and running. New scripts I develop in my tree to test them while Photoshop is up. I drop them on Photoshop from Windows File explorer. The next time I start Photoshop the new script I have added into my Photoshop Scripts tree will be in Photoshop's Script list.
I only add script plugins to the Preset/Scripts folder. Everything else is in it's own CVS managed folder and accessed via an Action in an Action Set. Although not a straightforward process, you can generate an XML file for a folder of scripts, convert the XML file to a .atn file, and load the .atn file into PS.
I guess this is the closest you can get to reload scripts in Photoshop. Thanks!