A "revert to default settings" item wouldn't be a bad thing to have in the script menu. Although some might say it would take valuable space along with the remote settings making the menu too cluttered, and it would be quite unnecessary if merely reloading the same script would clear the changes.
Meanwhile, to get back to the script's defaults, you can load some other script and after that load your newly modified script, since the settings are remembered for only the most recent script (or is there a way to save them for other scripts as well? This is actually something I'd like to see, maybe in the form of a "save defaults to script" option ... I know we'll be getting a file editor some day to partially solve this by another means completely).
Meanwhile (unless I'm mistaken about losing script settings on loading a different script), I'd vote for the settings to be always cleared when a script is loaded from the script file browser, even when the loaded script has the same name as the currently loaded script.
Retaining settings for the current script on power-off is another thing completely, it's a great thing to have.