Can you leave the leash on her inside while she's is going about her normal activity? I've done that with several foster pups who were leash averse. It allows them to get used to the feel and weight of the leash. We'd let them play in the house and in the backyard with the leash on until they are comfortable walking on it.

What I do with hard to potty train pups is give treats and praise like crazy when they potty outside. They tinkle or poop outside and they get tons of praise and treats! You could do the same thing when you're putting on the leash and while she is walking on it. Teach her that awesome things will happen (treats and praise) when she is on leash.

Good luck! Puppies are the best and worst at the same time.