It's a bit counter-intuitive but for dogs who remain focused on the lure it is helpful to allow her as much time as she wants to completely explore the lure once she catches it. Even if she wants to completely tear it to shreds (they're made of maize flour and won't harm her and the bits are compostable so they won't hurt the lawn) Let her take as long as she needs to become completely bored over the lure itself, she'll soon figure out that the fun is in the chase.
Chewing the line might be her way of celebrating her victory. So you may be able to draw her attention away from the lure/line with a lot of praise and an even higher value reward - for her this might be something that fulfills that desire to chew. She may have a strong instinct to hunt, kill and consume. The chase may trigger this predatory cycle and if you were to offer a chewy treat after her "kill" she may let the line loose. If you can get her to do this consistently - over time she will realize that letting it go after she catches it that the fun can continue.
You may find an even more effective way to teach her what you expect. It's really a matter of finding a way to fulfill her needs while you communicate what you expect from her.