I just stumbled on to this. It's so simple.
Find someone who is easy to rob. Whatever properties you are robbing continue robbing until you run out of stamina.
The most frustrating part for me was when I ran out of stamina I had to end my robbing spree, even when the person I was robbing still had some "life" left in their properties.
So this is what I tried. And it worked!
Open up Notepad in Windows or Textedit on your Mac.
Right-click on the person's name and click open in new window. You will open a window with that person's stats.
Now copy the URL and paste it on a line in your text editor. Save the file.
Back to your browser and open another browser window and paste the URL in the location bar.
See, you opened another window to the "mark's" stats page again.
Now you can do something else or shut down your computer and come back later to rob this person again.
When you've regained some stamina you just go back to your text file and copy the link and rob them again.
Look for the line that includes the link "Rob". Click on the Rob link and go to town.
Just be careful that you're not abusive. If you bully someone regularly you probably most likely would get your account shut down.