Yes, if for some unfathomable reason, you want to reset the budget value back to what is shown on the battery (e.g. zero out the "status") you can do it. Its kind of convoluted:
Set a destination on the nav system and make sure you answer yes to the "Will you charge at the destination?" question. Once the route is all setup and you see the display change from budget/status to charge pt/surplus cancel the route. When the route is cancelled the budget value will be reset to the current range indicated on the battery.
I've put a little more detail on this here:
http://jamiegeek.myevblog.com/2013/11/1 ... he-budget/
Ok yeah a quicker way would be to simply pull over and turn the car off and then back on again! LOL