Keep in mind that there is a preset limit, on what you can charge total. Values are $500, Mods $1000, and deluxe $1500.
You can however go ahead and let them run the charge through, and start over at zero again.
Example, we checked in on Fri. eve at Pop. On Wed. we were up to $417.00, so I had them go ahead and charge it to my account. By Fri, we were back up to $360.00, so I did the same thing, since we were going to Downtown Disney to do our final shopping spree. Then on the morning of checkout, they just charged the final $273.00. You can still use your room charge for the remainder of checkout day. Your CC, is just charged again, after your check out.
It is a great feature. We hardly carried any cash. Just enough in case we encountered a cart that could not take the room key. We used our key, for meals, kids clubs, and even our illuminations cruise.
Have a great trip.