I got the answer to my question - you set up your new device but on your existing account, and replace the old device with the new one. It's pretty easy and all the data I'd synced before is still there.
I don't think I'll be able to be a really active member of the group till I get an iPhone because right now I can't sync every day - I can only sync to my laptop and I don't turn it on every day. My iPad is too old to sync to it (which is one thing I find quite annoying). Anyway, I expect by the end of the month I'll be able to sync every day and throw down the gauntlet to y'all. In the meantime it will be good to know myself how many steps I'm doing and how many calories I'm burning.
I don't think I'll be able to be a really active member of the group till I get an iPhone because right now I can't sync every day - I can only sync to my laptop and I don't turn it on every day. My iPad is too old to sync to it (which is one thing I find quite annoying). Anyway, I expect by the end of the month I'll be able to sync every day and throw down the gauntlet to y'all. In the meantime it will be good to know myself how many steps I'm doing and how many calories I'm burning.