You can get replacement laces if you want. I believe you can order them directly from BOA. I does look like it would take some time to replace them though. A good hour I would bet. Then again, if you are watching for frays on your cable you should have plenty of heads up on when to replace them. I'm riding on BOA focus this year and I should get around 60 days maybe more as long as the snow flies. Plus I will be putting extra abuse on them with all the backcountry skinning I do. As long as the boot itself holds up (second pair of DC's I blew out the sidewall <20 days on the first pair) I should have an opinion about the durability of the cables.
30 minutes per boot tops if you're remotely coordinated or "mechanically" inclined. How do I know? I accidently popped the housing for the side reel out of my DC Allegiance (Duel zone) when I was walking down steps. Turned my foot too much at the turn in the steps without paying attention to where the reel was. Turns out they are REALLY simple to replace and work on. They provide a torque driver (though it is tiny) that is all you need to disassemble the reel and cable system. Because they were dialed in and taunt the only way for it to give was pulling the cable loose from the reel. I say it was simple to work on and fix because all you have to do is unscrew the wheel and then the screws that hold the cover for the housing to get inside of the reel.
1 - Unscrew reel wheel
2 - Unscrew holding screws in the cover of the housing
3 - Unscrew the set screws (When you look there is a metal tube inside the center of the reel gear (inside the housing) above the dial wheel that has 2 very small screws inside of the metal tube basically.)
4 - Place the cable ends into the holes on the reel. MAKE SURE THEY ARE IN ALL THE WAY!!! Paying attention to how the cables wrap around the reel you can see one side of the holes are rounded off to prevent fraying. That is the way the cables should wrap around the reel gear. (Also if you notice one end of the cable being longer than the other it's because they wrap in the same direction and so one must reach a little further around the reel gear.)
5 - Put the set screws back in and tighten them firmly
6 - Pull the cables taunt by wrapping them around the reel as you replace it in the housing
7 - Screw the cover back in place
8 - Screw the dial wheel back on and you're good to go.
Having done it once it only took me about 30 minutes even with errors and nearly losing a set screw, I'm confident that it can be done in about 10-15 minutes max even if you are taking your time and being careful.
WARNING! The set screws (2 tiny screws inside the metal tube if the reel gear) are VERY small. I suggest doing this in a well lit place where you're not likely to be bumped around and lose the set screws. Place the set screws in something so that they won't roll off a surface also. And if you're having to do this in the back country it's not a big deal. The set screws are black. Just find a clear area or pack some snow into a concave to set them in.
For the tongue reel it's even easier as the housing does not need to come a part.
1 - Pull the cable to get slack and set the reel wheel.
2 - Unscrew the reel wheel
3 - Pull the cable ends out.
4 - Screw the reel wheel back in and you're good to go.
Replacing the cables themselves is easy also since they are metal. All you have to do is run it through the guides and then start the end into the hole where they come out from the reel housing and then push them back into the boot.
If you're really worried about losing a day of riding to a busted cable, just practice it at home a couple of times and carry a spare(s). I would suggest getting extra set screws also. At least 4 of them if they aren't too expensive.
If anyone is interested or wants them, post and I'll disassemble mine again and post pictures of the process for you sometime later this week.