Repeated Error Messages About Replication Already Running
If you receive repeated error messages that replication is already running, you may have too many temporary files or expired rollback files stored on the server.
Do the following to help resolve this issue:
Stop the service.
Clean all files out of the %Commerce Server Root%\Staging\Packages directory, and then delete all files in the CSSTemp directories on the root of each drive. You will be unable to perform any rollbacks after you delete these files.
Restart the service and run the replication again.