It doesn't look like there will ever be a "Book of Eli 2." The first film wraps up its main story, ending with Eli's death after completing his mission to take the Bible to the printing press in San Francisco, and only leaves a little room for a sequel with Solara going out on her own.
According to Mila Kunis, it sounds like there's never been a plan to churn out a second film. When speaking to the Hindustan Times in 2010, the "That '70s Show" alumna explained that it doesn't need a sequel: "This would be a very weird movie to have a sequel, let's be honest. With the purpose of the film, I don't foresee it happening and I haven't heard anything. So I'm going to say no. I don't think there should be a sequel. I think the purpose of the story ends. It's done."
The book has been delivered, so a sequel would be pointless. Plus, there's been no word from Warner Bros. that it's interested in making a franchise out of it.