Use wfchmsg.sql to change the internal name of a message and update all references to the message. See: Change the internal name of a workflow object.

Use the script as follows:

sqlplus <user> @wfchmsg <msg_type> <old_msg> <new_msg> 
Enter password: <password>

Replace <msg_type> with the item type of the message you wish to update, replace <old_msg> with the current internal name of the message, and replace <new_msg> with the new internal name of the message.