I would also agree with recall, but I would work with stopping her before she gets to the fence. Like when you notice she is even starting to think about it. Is it possible to work with her in the fence in area, with no other dogs around? Letting her run around and interrupting her thoughts before she can think about it. Does she have a favorite toy that she can chase to help lure her away when she starts to get close. She already knows she can do it and that she's getting away with it, so in her mind she doesn't think she has to stop. So would think (and I'm just brainstorming with you) that you could find something to distract or stop her just before or anytime you notice she looking towards that fence. I too, have a mostly lab/husky mix, with a lab coat and I would disagree with you about being able to let her sled. My dog has had no problem with winter and learning to sled. Since she is a runner, it will wear her out, teach her to focus (mental stimulation) and may help calm her down. I also know how much of a spaz a lab can be, and she may be needing more mental stimulation and focus, which would give her more of a purpose, and in turn this may help calm her down. And since labs are retrievers, she may just need a good game of fetch to keep her mind inside the fence. Huskies are extremely smart, witting and caniving dogs, left to there own devices, they will find other ways to use those qualities.
I should know I have 5 husky/lab mixes!
I use clicker training. There is a tape or book called "click to calm" that may be helpful in directing her engery, so that she is not in constant need of so much physical exercise. Taking the burden off of both of you.
I have one dog, who's almost a full-blooded Husky, that when he was a pup he was quite the terror, I could never calm him down, and it seemed that he would just wind up even more. But when I started the clicker training with him, it completely grabbed his attention, held it, and he would begin to calm down. It was truly amazing, as I was almost in fear of this little monster because he was so out of control.
Your dog is still young, and lab's and huskies have a drive for running, so I understand what you are going through. All hell breaks loose if we don't go for our runs. I don't know if you are doing it or not, but it may help to be engaged in her playtime, instead of just letting her run loose with the other dogs and go crazy. I have found that quality play can make a huge difference than just quanity of it.
Even though my dogs have never jumped the fence, I have plenty of other behavor problems I am working through. And as with life, I'm just learning as I go.
Hope that helps a little. Good luck!