The first Paradigm to break for ProE users, or other history based users, is when creating your 2D profile, don't just throw down a rough sketch and expect to go back and add modify the profile by changing parameters. Build your profile with your final design in mind. The workplane and profile are tools that you use to create a solid model, and are not needed after the 3D geometry is generated. If you need to make changes, make your modifications on the 3D model. It is much easier.
