I hit this problem earlier using the factory setup of the blade 400. It took me a few batteries to figure out what was happening. Here are the symptoms, cause, and the solutions. Please note, this was only for my particular case. But it might be what is happening to yours too.
1) ESC cuts off at around 2 minutes.
2) Battery still half full according to charger.
There's actually another symptom: ESC is very hot. As it turned out, my ESC was cutting off because it was too hot.
1) Mount ESC on the side for better ventilation. I think this helped, but this alone didn't really solve the problem.
2) Reduce the drain from the motor. This was a combination of adjusting the throttle curve and the pitch curve. Please see my post about the setup here: E-Flite Blade 400 Beginner Setup for Hovering and Slow Forward Flight. (16 minutes of flight time!)
With the two solutions above. I have no problems with early cut-off anymore.
Other options you can try:
1) Fly without the canopy.
2) Replace the stock 25A ESC with one with higher rating. e.g. 35A
I hope this helps. Enjoy!