>What would be the best way to repopulate a listbox with diff values after the user has selected an orig value. In other words, I'm recycling the listbox.

Write listbox populating code in separate form.method and call it every time it is needed, e.g.
Myform.RefillListbox

Lparameters nRefillmode
With this.mylistbox
 .clear
 do case
 case nRefillmode=1
   .additem('item1')
 case nRefillmode=2
   .additem('item2')
 ....
 Endcase 
Endwith