I tend to let my cider sit for a month or so, sometimes adding additional sugar halfway through, to make it stronger.
To get the yeast to stop, wait. There is chemistry you can do to slow down the fermentation, but i've never tried any, and so cannot recommend or advise on possible flavor changes. You will end up with dry cider this way, but you can always serve it with a simple syrup to re-sweeten to taste.
I personally make the syrup with 1 part water to 1 part brown sugar, sometimes with a cinnamon stick or some cloves in for interest.