I dunno. I had to do the same thing yesterday, and the only way I could find to do it was to cut and paste and basically recreate what was in the test vault to the live vault. I couldn't find any easy way.
You cannot import a new workflow on top of an old workflow. You have to manually duplicate the changes in one to match the other. This deficiency is noted in SPR 647969. I have two vaults, one for production and one for development where I try things out. When I need to update the production workflow, I open up one workflow on each monitor and go through them from top to bottom making sure all the changes in the development vault are made in the production vault.
Also, having taken a quick look at your workflow, one suggestion I have is to number your transitions so that you can control the display order in the Change State menus. For example:
1. SUBMIT FOR APPROVAL
2. NO APPROVAL NEEDED
3. EDITING REQUIRED