Plugin will allow status change of a ticket on new reply by user.
E.g. you may have two Open status "Open" and "Awaiting Client Response". This plugin can be configured to automatically change the status from "Awaiting Client Response" to "Open" when a reply is received.
https://github[dot]com/stefanclark/osticket-statuschange
I couldn't find this functionality by default. osTicket allows status change from a closed to open status, but not open to open.
Feedback welcome