How much did the battery replacement cost? Mine's still ok, but it probably won't be long before I'd consider a replacement. But that does rather depend on the price...
I did a DIY on my 2011 Air for $70ish and while it seemed to solve my problems at first, after a short while it seemed like every time i went to use the machine it was dead. (I only use it once every week or three). I'm not sure if it's not sleeping, or waking from sleep, or what. I use it too little to even troubleshoot. But that was enough to get me to pull the trigger on a new i9 Air yesterday.