Well, sugar is fermentable, so some people add sugar to boost the alcohol level. Without added sugar, I think cider is in the 6-8% ABV range. (I'm not sure about that, though!).
I prefer my ciders and wines dry, so I don't add sweetener to it after fermentation. If you find it too dry, you have several choices. If you are not carbonating, you can stabilize the cider by adding some sorbate and then sweeten with honey or sugar. If you are carbonating, you can use a non-fermentable sweetener, such as lactose or Splenda.
I'd wait until it finished up, and try it and see how you might like it best.
Edit- Wow- tusch is faster than I am!