Yep - string can get caught in the digestive tract and cause all manner of problems. What about Pounce and those kinds of treats? People belive - mistakingly that if they give their cats these treats the tartar on their pet's teeth will be controlled. That is not true. Do we get rid of tartar by eating anything? There is only one way - with a cat toothbrush and special toothpaste.
I cannot think of other kinds of chews though - seems to me just giving her something to play with might help - a mouse, a ball?
And trust me, you;ve never seen chewing till you have a bunny. My bunny - who lived to be 13 - after I was told "Oh he'll live to about 5, lol) - loved to chew- tables, wood, denim jeans, cell phone cords, telephone cords - especially if one was on the phone. My home became wireless very quickly, lol