TFS2015 - Refresh work items after work item template change

I'm using TFS 2015 Power Tools for Visual Studio 2015. I've added a new State to the work item workflow and updated the transitions accordingly. I can see that the workflow is updated for newly created items.

But is it possible to update my existing work items with the new workflow?

I have hundreds of work items and I want them to use the new workflow for them.

Solution

Based on my test, the new workflow will also effect on the existing work items.

Please note that the existing work items must be in the team project which you applied the new workflow and match the specific work item type.

If the new State does not appear on the existing work items, then just try below items:

Edit WIT in web portal:

Refresh the web page

Edit WIT in VS:

Refresh on Team Explorer (Work Items Panel )
Restart the Visual Studio

Then try it again.