Displaying note with new pitch

Hi,

I'm working on converting the minorvariations plugin to the new API and I want to do this

note.pitch++;

and have the note redrawn with its new accidental. When I add one to the pitch, nothing happens in the score. Changing the colour results in an immediate change of colour, but changing the pitch does nothing. How do I get the note to redraw?

thanks
Samantha