you could get a repository backup from the Adin Console, then change your repository database properties and restore it.
Please, let me know if this solution is useful for you.
Actually you can find these steps in KB119173:
1. Confirm that you can connect to the new database (use SQL*Plus or any DB query tool) from the node where the Informatica Services are located.
2. Login to Administration Console.
3. Stop all Integration Services in the repository.
4. Backup the repository.
5. Stop the Repository Service.
6. Configure the Repository Service to connect to the new database (Properties > Database Properties). Update the connect string, database type, database username, and database password (ConnectString, DatabaseType, DBUser, and DBPassword).
7. Enable the Repository Services in Exclusive mode.
8. Restore the repository in the new database.
9. Restart the Repository Service in Normal mode.
10. Start all Integration Services in the repository.