How do I get better Autofocus?

I just got a 14mm Panasonic lens for my GH2. However, I'm quite new to this and wanted to learn how to get more continuous/steady autofocus.

My videos have a lot of a movement away and towards the camera. I shoot review videos and have to bring the product close up and set it back down again. Trouble is, the camera keeps focusing on a small bit of the video instead of the whole scope (Like my old camcorder does). This results in the video constantly focusing/refocusing whenever I move my hands and it looks terrible. Sometimes it doesn't focus at all!

Is there any way to configure the autofocus to perform better? Any settings in the GH2 or techniques?

Thank you for reading.