WLT_CSV Plugin – is there a way keep categories when "deleting all listings"?

I’m sure it’s a simple(?) PHP line in there somewhere – but I’m 100% newbie when it comes to PHP so I have to defer to others who speak this language. Basically, the reason I need to keep the existing categories is because I intend to use the [LISTINGS] shortcode which requires a numerical ID to identify a category. However every time the “delete all listings” button is pressed in the WLT_CSV import plugin, those categories are lost and new ID #s are assigned to the fresh import (even if the category names are the same).

I hope I have made this clear enough… Any help with specifics (read “very specific” 😉 is most appreciated since theoreticals will probably be lost on me at this stage. If this needs to go to a job board, I’ll understand – it just seems like it should be a simple equivalent of an “on/off” code that determines whether or not the categories are deleted…? Thanks!