Chose which section best suits your situation.

Section A
Is for those that still have the original blueprint that was used to upload to the workshop.

Section B
Is for those who may have lost or inadvertently deleted their original blueprint.

1. Load your self into a world if you have not done so yet and then open your blueprints (F10) and now find the new blueprint you want to use to update your current work on the workshop and at the bottom right side you will see a "copy to clipboard" button click that to copy it to the clipboard.











2. Open your blueprints again (F10) and now find the original blueprint you used to upload to the workshop and again at the bottom right side you will see a "replace" button click that to use the current blueprint you have in your clipboard to overwrite this blueprint and once you have done that you can now hit the "publish" button and it will update your current workshop blueprint.











When viewing your original blueprint on the steam workshop you should see a number next to the change notes and date it was updated ( view ) at the top right of your workshop item.

1. Navigate to your blueprints folder/directory on your computer C:\Users\--YOUR PC NAME--\AppData\Roaming\SpaceEngineers\Blueprints\local

2. You should now see all of the blueprints you have created. Open the folder/directory of the blueprint you want to use to replace your current workshop item with and go in to the folder, You should now see a file named bp.sbc, bp.sbcB5 and thumb.png.

3. Open the bp.sbc file with notepad++ or your favourite text editor.

4. find <WorkshopId>0</WorkshopId> CTRL+F to find and search for <WorkshopID> or (scroll right to the bottom usually its at the bottom of the document)











5. You will want to replace the number between <WorkshopID> and </WorkshopID>. It should be 0 if you have never uploaded the blueprint to the workshop before as the blueprint would be considered to be a new blueprint, It will show another random number if you uploaded it trying to replace your current workshop blueprint, once you have changed that number between <WorkshopId> and </WorkshopId> to your current workshop item id number save the file.

6. DELETE the "bp.sbcB5" file.

7. Load up your SE game in creative mode and open your blueprints (F10) and now find the blueprint you just modified and paste it into your world, doing this will create a new "bp.sbcB5" file, this is something that i do to make sure the "bp.sbcB5" file has been created before i publish.

8. Now click the publish button and just follow the steps thought and it will replace it automatically, When viewing your original blueprint on the steam workshop you should see a number next to the change notes and date it was updated ( view ) at the top right of your workshop item.











You can fined the WorkshopID number by going to where your Workshop content is and by viewing the blueprint you want change it should show the ID number in the address bar at the top left.
you can also find it by googling "space engineers workshop" and search for your blueprint and in the web address bar it will give you the id number.











Final notes
After competing this section You should only need to do this once and there after refer to section A if you need to replace your blueprint again.