I have had that wifi disconnection from time to time but it has not been consistent. Anyway, I've just installed the app Auto WiFi Enabler. You might want to check into it to see if works.
6-3 update: Auto WiFi Enabler seems to be working well. I normally turn off my wi-fi setting in the general settings and I'm leaving Auto WiFi Enabler setting in Automatic Mode. From time to time, if I check my connection, I see that wi-fi has magically turned itself on.