Success! agmg, you are BRILLIANT! Just17 ... my hats off to you, as well, since you had suggested that I might have a second hidden panel running amok on my screen.
Here's what I did. I opened up the plasma-desktop-appletsrc file, like agmg suggested, and searched for plugin=panel. Come to find out, there WERE two panels defined ... one for screen=0, the other one for screen=-1. So, I made a backup of plasma-desktop-appletsrc (just added the .bak file extension to it), then deleted the section that contained the panel plugin for screen=-1. A simple logout and back in to restart plasma-desktop, and now everything is back ... including my NetApplet!
Thanks a million, guys! I'm marking this one SOLVED.
Glad my post was useful.
When I read Just17's post, I was sure I had encountered something similar in the past.
Searched my notes and found it