"I have used the monetary reward system and it worked - until I lost my job. I am a single mom who has been unemployed for 16 months. My unemployment cut off 4 months ago and my savings was depleted even before that. Are there any ideas that do NOT involve money? I haven't been able to think of anything other than praise and encouragement. I no longer even have a car."
My first thoughts are giving a privilege of maybe a later curfew or an extra hour of computer time. I also think that your teen could clue you into what they might like as an incentive, so don't forget to ask them.