Hi t_b, you need to use the update app. Just make sure you have enough power in the battery as you don't want anything cutting out when it does the update.

As a general observation, my EE hibernated overnight and woke up without problems this morning.
Battery life is very good - up for over 24 hours with over 50% charge left, OK it was sleeping overnight but in the same conditions before I would have to charge first thing.