I dont know it this has been asked before, but i couldn't find anything searchin, so...
How about making different chains of commands (or what to call it) in NV?
For example, when i tell it to launch my gps program it asks me if i want to go to any preset location. If I do (saying "yes" =P ) it asks whitch one of them, and when i say for example "home" it sets home as destination, and then stops voice recognition. If i do not want to go to any preset location i just say "no" and then it stops voice recognition.