You can boot into recovery mode by holding Shift and R when you restart – this will allow you to do a fresh install of the OS. However, you'll have to watch out for the update, if that is the cause (it seems likely), and not install that.
To be honest, having been through the process over the last month, and tried many settings, reinstalls, resets etc, if you want the problem to go away, make the autopoweroff change in Terminal. You can easily put it back again when (if) an update comes from Apple. If in doubt, turn it back on after the next update to see if it's cured – it's what I'll be doing.
Enter Terminal (scray name, but it's fine, then do the sudo pmset -a autopoweroff 0 command. If you want to turn it back on, type sudo pmset -a autopoweroff 1
Mine was also a refurb (great way to get them a little cheaper). Approaching AppleCare is a good idea, but if you try some basic setting changes, it'll make it easier for Apple to narrow down the problem. It's not going to helps them if everyone goes in blindly after we've all spent so long narrowing down what appears to be the root of the problem.
We don't know that Apple are ignoring the problem – take a read through some of the posts here, and imagine trying to solve an issue based on them. Instead of being annoyed, try the setting tweak. If it works, be happy, and ask Apple why. If it doesn't, then you've not lost out anyway. Why not help Apple fix the problem... they're only human too (I assume).