Martin,
The lessons you watched for The PM PrepCast (for CAPM) are identical to the ones for PMP. So you will not need an upgrade for the video lessons. The difference is that those lessons listed as "optional" for CAPM, are now mandatory as you are preparing for your PMP.
However... the CAPM Simulator and PMP simulator are (of course) vastly different. But there is no upgrade. So you will have to purchase a new license for the PMP simulator.
Tip... we currently have a discount coupon and you can get it for 10% less by visiting
www.project-management-prepcast.com/discount-coupon
. And since the simulator "waits until you take your first exam" you can buy it now and just let it 'sit and wait' until you actually need it.