Well it sounds like you upgraded on her line, and then xfered it to your number? If thats true, then no. Your contract has since expired. You could simply upgrade your line if you want, and get a new phone. It would put you both under contract until hers expires in December, but wouldn't require her to have a data package, unless she has a smart phone too.
I'm confused about upgrades like this. I upgraded to my Inc2 12/19/11, using my wife's upgrade, so that extends the contract to 12/19/13. My line has an upgrade available since 4/26/12 and hers will have an upgrade available on 8/19/13. She has a basic phone. If I use my upgrade now, we would have both phones on contract for a smartphone. Could she still keep her basic phone or would she need to go to a smartphone and data plan until the 12/19/13 contract is up from the Inc2 upgrade?