Color Finesse 1.x and 2.x are considered to be different plug-ins. They co-exist nicely, so you didn't need (or want) to uninstall 1.5 when upgrading to 2.1.
We did this so that existing project wouldn't render differently depending on which version of Color Finesse happened to be installed.
To upgrade an existing project you can save the Color Finesse settings for each clip, change which CF version is applied, then re-load the settings.
Bob Currier
Synthetic Aperture