Unless there is a custom setting option when you run the updater, you will have to uninstall AC and then reinstall.
Typically I download and install all available goodies, such as the 3DStudio in/out, when I first install AC. This avoids situations like this
and you are set to go when you want to use them.
Before you uninstall AC, move any of these add-ons out of the AC installation so you don't have to re-download them
Erika
Architect, Consultant
MacBook Pro Retina, 15-inch Yosemite 2.8 GHz Intel Core i7 16 GB 1600 MHz DDR3
Mac OSX 10.11.1
AC5-18
Onuma System
"Implementing Successful Building Information Modeling"