Nope, it doesn't work that way. The developers had to develop these apps twice. Though much of the code can be shared in a lot of instances, they are essentially different apps. In the same sense that if you have a Ford Focus and a Ford Fusion and get a
set of new tires for the Fusion, don't expect them to magically show up on a the Focus.
That said, it would be a great model if this could be perfected, or if WP apps could run in the side bar w/o the developer having to significantly recode. Or if Microsoft would make available a discount mechanism for the developer to enable at their discretion
for loyal app purchasers.