I am using the DuoLingo app each day, and have bought German children's books to read to her, which will also be good for me, but a few other things that are helping in the "immersion" goal are:
The Slow German podcast at SlowGerman.de - a podcast of German information and news read very slowly so that non-natives can easily follow it. This is great!
I also found MySpass.de, which streams German comedies, full episodes, for free. This serves multiple purposes. First, since I'm feeling old and tired and sore, and eating lactation cookies and drinking fenugreek tea (I'd never heard the word fenugreek three months ago - now I'm obsessed with it), laughing at German comedies I can't understand is awesome. And of course, it's helping me learn the language. But the laughing at weird German stuff I can't understand is really the highlight right now.
In addition to the fact that growing up bilingual will help her brain development, and make it easier for her to learn new skills as she gets older, I just plain like the idea of having a second language that I can speak with Hannah, kind of like our secret language. Not too many people in Southern California speak German, so we can have secret conversations, and I can't think of very much that's more awesome than having mother/daughter secret conversations.