You can always change the JDBC datasources in the Weblogic admin console . but have you recorded what is the specific error you got during the datasources creation .
I prefer...create a new user , give him sysdba privillages . Start RCU and create the DEV_DISCOVERER , DEV_DISCOVERER_PS schemas (prefix is your choice)
The Admin server will start . so go to admin console .
click services -> Data Sources
Check the data sources you have . edit each datasource and update the connection pool information .
after this you can start the Managed server WLS_DISCO
i believe this will solve this .........
if you still get issue again . you can try the link Using the WebLogic Persistent Store