After a session completes successfully, the Integration Service saves the final value of each variable in the repository. When you do not want to use that value the next time you run the session, you can override the value in the parameter file or the pre-session variable assignment in the session properties.
When you do not want to use any of the variable values saved for a session, you can clear all saved values. You can clear variable values for a session using the Workflow Manager. After you clear variables values from the repository, the Integration Service runs the session as if for the first time.