Change in existing workflow don't trigger the webservice

Hi Team,

We are in IP15 and my query is we have an existing inbound web service which triggers a workflow. I have some changes to the worklfow so, I have introduced new steps but without introducing any new property sets and no changes in existing property set. But I see the that the workflow is not getting triggered.

But when I create a new workflow and and deploy it as new webservice, it triggers the workflow and we are receiving the response.

As we have already shared the wsdl to external team, we cannot give a new wsdl with them.