1. Delete the installation package from the group and apply a new package to the group with the same client version as the currently deployed clients.
2. Uncheck the maintain existing features checkbox and specify the client features you want installed on the client.
3. In SEPM 12.1 You will also get a option to select the client installation settings,
a. Create a client installation settings from "Admin" tab , "Client installation settings" with the option "Remove all previous logs and policies, and reset the client-server communication settings ".
b. Select the settings created while adding the installation package.
Note: This will likely require a reboot in order for the update to occur. There have been some cases where this workaround was not effective. If you run into a scenario where the client is not adhering to the newly assigned install package, then try moving the client to a different group within the SEPM so that a new package will be assigned or manually modify the feature set for that client via Add or Remove Programs->Symantec Endpoint Protection->Change->Modify->Choose the features you wish to add. If that is still not effective then proceed to the second workaround below.