Airbag Senor question

Can someone tell me if the airbag sensor need to be replaced once it is tripped? Does the sensor remain tripped? Can it be reused/reset so I can just install another airbag? Any help on this subject is greatly appreciated.

[Earthworm]

According to Subaruparts.com another sensor assembly is $274.31 and another air bad is $622.29. I'd rather replace the sensor just to be safe than hook up the new airbag and have it go off and cost you another airbag.