A school could cancel a snow day and then resume school if the weather clears up and the road conditions improve the next day before school opens.
However most schools who do close school down for a snow day or other winter weather event will usually remain closed for the day.
Then they will resume school once the weather clears up and the roads are clear enough for safe travel.
I've never known a school to actually cancel the snow day after they already canceled school for the snow day or other winter weather event.
Most schools once closed for the snow day remain closed until the next day at least or until the weather gets better.