Go to Schedule and change the setting to Every Time, then Run Once.
You can run any campaing as many times as you want, but the Qualification Rules determine how many times the smart list qualified folks can go through.
Once you are done testing (this is a "Live Test" you are doing), then change the Smart List.
Usually I recommend cloning the campaign and updating the smart list because the Run Count and Qualified Counts will add up with each test, giving you a slightly wrong number for your reports.