Granting Workflow App Permission in Site after changing Site URL

Hi,

I am working with SharePoint 2013 and SPD 2013. I have a site that previously, I activated the "Workflow can use app permissions", looked up for workflow app and granted it elevated permissions byadding Permissions Request XML like this article http://msdn.microsoft.com/en-us/library/office/jj822159%28v=office.15%29.aspx.

My workflows worked before, but after I changed my site url, I got unauthorized 401 in my workflow. I looked up for the workflow app again and saw that in the Redirect URL field, it specified the old URL of my site and I cannot update it. How can I handle this?

Thank you.