The basic rule I recommend is use disabling when a command is currently not available but the user can do something pretty obvious to make it available. I think that fits your situation here. Presumably you have some indication whether each survey is submitted or not (users will need this to know which have been de-submitted and need re-submitting. If all surveys are in the “Submitted” box or have the Submitted field showing “Yes,” then it’s pretty obvious why the Submitted button is disabled, and what would enable it.
Hiding should only be done for controls that are essentially never available to the user (e.g., they don’t have permissions). Otherwise hiding them is confusing: the users won’t know if the command is simply unavailable or available but they forgot where the button is. You shouldn't rely on the user noticing and remembering little changes in the UI (e.g., a button used to be here). Hiding the button also can disrupt your layout, causing inconsistencies or false control groupings.
Changing the label to "Submitted" is non-standard introduces the chance of confusing the user. Apple OSX guidelines specifically prohibit using a button as a label (p231). Such guidelines are good places to get recommendations for questions like yours.