how to change workflow completed for items with programming

In SharePoint 2010, i created an info path form and submitted it to SharePoint.

With Microsoft SharePoint designer i created a workflow for this form.

At this workflow I implemented removing permission from some group and getting contribute access to 2 person.

Now after 3 month, there are 450 item in form library.
And i want to add another person to (2 persons) that have contribute access now.
So, i changed workflow in SharePoint designer.

It is correct for new items that created after this time. but i want this new workflow set to old item that before 3 month created!

how can I do that?