Generally, software updates through the Mac App Store work smoothly, and simply update the application that you already have installed.
However, this process can occasionally get hung up and not work. In this case, you can simply delete the application, and then download the newest version of the software from the App Store.
To do this, navigate to [Your User Name]/Applications, locate the application you want to remove, and drag it to the Trash.
Then go to the Mac App Store and click on Purchases. Find the updated Strata software, and download it again.