1.Keep old version dll
a.Create a folder named as version1.0.0.0 in Bin
b.Copy existed workflow DLL from GAC(differnent between SP2010 and SP2013) to created folder
2. Modify old version element file of workflow
<Workflow
Name="PurchasingWorkflowTempalte1.0.0.0"
Description="Purchasing Workflow Tempalte"
Id="041b72c8-6491-4a3d-9272-03d09f50f6d9"
CodeBesideClass="SP13.PurchasingWorkflow.PurchasingWorkflow.PurchasingWorkflow"
CodeBesideAssembly="SP13.PurchasingWorkflow, Version=1.0.0.0, Culture=neutral, PublicKeyToken=fe0afbe7fc302259"> </Workflow>
3.Package the old version dll for old workflow
a.Add existing dll and specify the [Location],In [Location] you must add route path.
4.Add definition for new workflow
a.Generate a new guid for new workflow template.
<Workflow
Name="PurchasingWorkflowTempalte2.0.0.0"
Description="Purchasing Workflow Tempalte"
Id="9B8AF2D0-6B36-4027-BAB9-53B5E0C54161"
CodeBesideClass="Leoni.SP13.PurchasingWorkflow.PurchasingWorkflow.PurchasingWorkflow"
CodeBesideAssembly="Leoni.SP13.PurchasingWorkflow, Version=2.0.0.0, Culture=neutral, PublicKeyToken=fe0afbe7fc302259" > </Workflow>
5.Modify assembly version and file version to 2.0.0.0 of the project.