The problem with semi-sweet, bottle carbonated ciders is that the yeast can continue fermenting to very dry and result in over carbonated drinks, or worst case dangerous bottle grenades.
One option that people have used is heat pasteurization once the desired carbonation is completed and sweetness level. I have not tried it, but it is basically heating up a large pot to around 160F, and then placing the bottles in for around 10 to 15 minutes, then removing the bottles and letting cool. There are threads here that describe it, but a search fails me right now.
Edit: OK, it's a sticky at the top of this cider forum, its 190F, and well just read that thread. I need to get some sleep.
In Primary: Belgium Chimay clones.
In Secondary: Braggot, pale ale, end of the world white.
Conditioning: Mead, Cider, braggot, Belgium Wheat.
On Tap: Clones, Chimay Blue, Red, Porter, malted cider.
Bottles: Far, far, too many to list.