We have a dial that only goes up to an hour to control our fan so we are continuously getting up and turning it for another hour. Can this be replaced with a longer timer dial, like 12 hours?
If this is a standard fan (i.e. no smart switch), Intermatic does make a 12-hour mechanical timer (no neutral required). If you want a programmable switch, you'll need a neutral wire in your switch box.
Yes. If you mean a standard spring-wound timer that doesn't require a neutral wire, those are made in a variety of ranges. 15 minutes, 30 minutes, 1 hour, 2 hours, 4 hours, 8 hours, 12 hours, or values in that general area. With, or without, an "always hold on" function.
Just buy a different one, they are under $20.