You can move a VM to another vApp within a vDataCenter.  At the time you move it, the VM must be powered off and may not have backups enabled.  

From the VM's detail page, click the Move button displayed among the page's top matter.  On the  resulting "Move VM" page, select the Destination vApp to which to move the VM.  

The display of the destination vApp's estimated cost reflects the proposed VM move.     

From the "Move VM" page, you can also set several other VM configuration values, as from the "Create VM" page. 

Click the Move VM button to submit the move request.  Task History records completion of the move.