Update README.md

README.md

@@ -292,6 +292,14 @@ Please make sure all steps described above work as expected before proceeding.
    If you do not see your result after 24 hours please contact us via email or the forum and provide your algorithm name and date/time you submitted in Central European Time.
 
 
+### Re-submitting if you make improvements
+If you already have an algorithm on Grand-Challenge you do NOT need to make a new one whenever you have made some improvements or changes to your code. 
+To re-submit, first just update your existing algorithm as follows:
 
+If you used **OPTION 1** in previous steps and uploaded a tar.gz file then you can now upload a new tar.gz file which will overwrite the old one.  Find your algorithm at [https://grand-challenge.org/algorithms/](https://grand-challenge.org/algorithms/).  Click on "Containers", and "upload a container" as before.  Allow some time for the algorithm to become "Active" as previously. 
+
+If you used **OPTION 2** in previous steps and allowed Grand-Challenge to build from your repository then a new build will start automatically whenever you tag your repository.  So just tag the repository and allow some time for the new build to start and complete, it will then show the "Active" label.
+
+**OPTION 1 AND OPTION 2**:  Whichever option you use, once your algorithm is updated you need to resubmit to NODE21, this does not happen automatically!  Visit the [NODE21 submission page](https://node21.grand-challenge.org/evaluation/challenge/submissions/create/) and proceed to submit to your chosen track as before.