How can I add a "Recurring" filter to core "Repeat contribution" report?
Over-riding core file would be last thing we should do unless there are no other option, since you need to port the file in each incremental upgrade.
Instead I would do one of the below

To add filtes, fields etc to report i would implement hook_civicrm_alterReportVar via extension or module or plugin

If the requirement is too complex than i would create new report file extending Repeat Contribution report(see example)