trying view the pop up – problems

I can view the pop up inside optin monster but as i tweek the look, i need to clear the cache. if i clear the cache each time which is time consuming (relogin to admin of site and optin monster) I also have subsequently tried to view the pop up in Firefox and Safari with no luck even after clearing cache in each of those browsers. I also tried incognito windows but still no luck…. Any ideas of how i can view this pop up easily?

The page I need help with: [log in to see the link]