system one heated humidifer

I have a system one I have had it about 6 mo. about 2mo. ago I overslept and my humidifier ran dry for about 1hr i normally have the setting on 5 so I don't wake up with supper dry mouth. now it seems the the humidifier is not working very much it uses like 15% of the water in the chamber now how do i get it to work correctly now. I can only sleep about 2-3 hr max now and I have bad dry mouth now and i don't get a full nights sleep. do they make a larger tank for the system one or other heated humidifiers