They do auto update. The thing is with it being a Beta they only update 1 time a day right now. That is how it is programmed. The other updates, if any others are available, are then released via Windows Update. This will change before it goes final to the public where it will query the server and check for updates 3x a day.
Right now being a Beta this is how it works. There is no option to have it check more often other than opening the software and hitting the Update button.