Archer's back on the ship, Enterprise is merrily on her way, and the entire 31st Century storyline seems to have been wiped out due to internal logic, although I fully expect some convoluted use of treknobabble and badly-conceived plot devices to restore it soon enough.
That seems a bit of a stretch for a reset button. I see your point, but to me, a reset button is simply when the events of an episode(s) are "reset" and have never occured due to some weird time-travel screw-up or something and nobody remembers what happened. Thankfully, that hasn't happened on Enterprise yet. :)
Now, if Archer had been stuck in the 31st Century and actually had to take a few episodes to figure out what was going on, and Enterprise had been forced to limp along without Archer, or someone was offed, or Enterprise was sent home, or something significant, I could have been impressed.
May or may not have been nice. I would like to see something similiar to that in an upcoming ep or something, as long as it's done well.
Instead, we were right back, plotwise, to where we started, minus 3000 colonists we will never hear from again unless TPTB have a real good surprise up their sleeves.
IMO, that's not really a reset button. The TCW story will be revisited in later episodes for sure. Things may be somewhat back to normal for now, but who knows what'll happen. These things may be revisited later this season.