If you're sure there's no one else (and I don't know how you could possible be sure) then do whatever you want. Go to the bathroom to change your shorts, reload while standing on your head, take a drink directly from the slurpee machine.
If you're not sure that the situation is over, stay behind cover, don't play around with your gun unless it's empty and needs to be reloaded and either call the police or wait for the clerk to call the police. Unlike the typical CHL/CCW holder, the police are trained to and get paid to check the scene after a shooting to see if there is another armed punk hiding behind the potato chip display. The officer responding will have a bullet proof vest and an armed partner to provide cover. You will have neither.
In other words, the scenario has the defender doing LE work--clearing the scene in this case. That (or a military-type mission) will be a common theme in any scenario where a tac-reload even makes a little bit of sense.