We're in the process of bell training too! Lucky you, Bella already "gets it"! Frankin and Maggie are terrified of the bell and I have to force them to touch it. I think we're going to have to teach "ring the bell" and then gradually transition to "ring the bell to go outside".
I did read on there that you have to take them outside every time they ring the bell to reinforce the training. It was emphasized that once the dogs get it, they like to take advantage of it. I don't know since I haven't successfully bell trained but from what I understand, you should just stick with it and hopefully the novelty of it all will wear off. Good luck!
