You might be asked to deploy new set of applications or update the existing applications to new release. In that scenario you might decide to update the existing AppDisk assigned to the users. At present Citrix don’t provide any option to upgrade the existing AppDisk as there is no version management built into AppDisk. This means every time when you need to add / update the application, you are cloning the existing AppDisk, making changes to the cloned Appdisk and assigning back to the Delivery Group. Another important point you need to remember is that, you CANNOT resize an AppDisk while creating a new version. As of now there are no option to resize an AppDisk within Studio. You would have to resize the AppDisk at hypervisor level and then reimport and reassign the AppDisk.
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Updating an AppDisk
To update an existing AppDisk, Logon to Citrix Studio. Select the AppDisk you like to update and select “Create New Version” from the Action pane. Select the Machine Pool to be used for preparing virtual machine required to update applications. This start the AppDisk creation process. Once AppDisk sealed after updating / Adding application, AppDNA compatibility analysis will be carried out against the preparation VM machine catalog. Once you have new version is ready with all the updated / added applications, you can assign the AppDisk to the required delivery group and unassign the old one.
Login to Citrix Studio and Select the AppDisk to update. Click on Create New Version.
Give the appropriate name and click OK.
Select the new AppDisk and Click on Install Application.
Login to the desktop and install / updated the required applications. Once Installed / updated, Click on Seal AppDisk.
After sealing the AppDisk, AppDNA will perform the compatibility analysis. Post analysis you can check the report for any compatibility issues. 
You can also view the reports after login into AppDNA directly. 
In this post we covered the process to update an existing AppDisk. I hope this will be informative for you. Thanks for Reading!!. Be social and share it in social media, if you feel worth sharing it. Happy Learning 🙂