How cold is cold? I let my ciders sit in my basement, air temp 63, usually use a wet towel on the carboys so would guess liquid temp 68 or so using an ale yeast.
When it's done fermenting and sat a little to ease out some off flavors (3 weeks or so) you can add more sugar, or apple concentrate, or something like that in order to have a sweet cider, compared to a dry cider which has nothing. The problem is, you will need some way to stop the yeast from consuming the added sugars. Your options are using a chemical to stabilize, which I've never done so I can't advise, cold crashing then keeping it cold so the yeast are dormant, or pasteurizing to kill the yeast. All this gets a little complicated depending on whether you want it carbonated or not, bottling vs. kegging, etc.
Here's your options:
- Dry, still cider - just put it in a bottle
- Dry, carbonated cider - bottle it with a little priming sugar like you would a beer
- Sweet, still cider - sweeten, bottle, stop fermentation as described above either before or after bottling depending on method
- Sweet, carbonated cider - sweeten, bottle, let carbonate, then stop fermentation
If you do the last, definitely read the stickied post in the cider forum. Good luck.