I think they're keeping Lori around for one reason:
In season 3, her baby will be still-born, as a teensy-weensy zombie (a la "Dawn of the Dead" [2004]), and bite her on the way out.
Oh, and it will look just like a little "Shane", big shnozz and all.
LOL!! It’s going to be a looong seven months till October..
How does a baby get infected in the womb of a living mother with the zombie virus?
Here’s why:
The baby is Shane’s. Conceived before the virus. The placenta keeps this baby from the virus. Lori knows it’s Shane’s she lied. She has to admit this before birth. If the virus is airborne they will have her deliver in a sealed sterile room and use either the placental blood or baby’s blood to work a ‘potential cure’ storyline. If the virus isn’t airborne, the sealed sterile room doesn’t have to exist to use the blood but the cure storyline can still go on.
Then she will cry about Shane dying and his ‘gift’ to all of them. Really not liking the bipolar nature of her character.