I'm not sure about maximum time limits and set draw dates, but you could probably have the lottery good for a year, or, until all the tickets are sold.
Right now, people are buying lottery and hospital dream home tickets like crazy out here.
It seems that the more desperate people get, the more they gamble.
Dropping the price to $25, and printing 6000 tickets might help, too.
Most people would probably buy more, anyways.
You also have your webpage to advertise on, and your walk-in crowd, as well.