By "kick out", I'm guessing you mean the auto switch turns off due to lack of bass for a period of time.
Most sub amps come with an "auto on" feature that, when a certain level is detected on the input the sub turns on. However, if you're listening at low levels or the program you're watching doesn't have a lot low audio, the bass may not be enough to trip the relay in the sub amp to turn it on... or keep it on.
The best solution would be to turn up the "LFE" level on your receiver and lower the level on the sub amp to get you back where you were started. For example, on my receiver, the sub level is set to +10 db and then I calibrated with a level meter to set the level on the sub knob. So, the receiver is sending a stronger signal to the sub, but it sounds the same since the sub amp is turned down a bit.