@p3079 when you reset you do not lose the updates you have done, you just lose any data etc on the watch - so make sure that you sync prior to doing this step.
Once you have done it, you will have pair the watch to your new phone, which will initiate the whole set up process again. If you have correctly set yourself up most if not all your details should be backed up and should come through when your set up.
All you should need to do is install any apps that you previously installed and want to keep on the watch.
@horvathbotond TBH the Spartan could do with a Barometer widget on a watch face or at least a Baro trend arrows for the past 12 hours that way you can have a quick glance and know what the pressure doing