In this post I'll present a list of the supported edits you can do in real time in blender and have all your render nodes updated without any upload. This list is intended to grow of course and over the coming releases we'll add more and more operations you can do that won't require you to upload the blend file all over again.
Anything that is not on this list won't update in real time and will require you to re-upload your blend file.
Transform Edits to objects
Specifically, moving, rotating or scaling an object is supported in real time. You can use any of the available methods in blender that cause these operations to happen, such as the manipulator, using the G, S and R keys, or by opening the properties panel for the object you want to edit and changing the values of the location, rotation and scale values.
Duplicating and Deleting Objects
You can duplicate and delete multiple or single objects by simply selecting them and using the normal blender controls to either duplicate or delete an object.
Undo and Redo
Both undo and redo are updated in real time. However this can only apply where you have been carrying out edits that are actually able to be synchronised in real time or in other words, those that are on this list.
Changes to the Render Settings
Any changes to the render settings that are contained on the render properties panel are updated in real time, including changes to the render layers, creating a new render layer and changing the passes for each layer. This works for cycles specific render settings as well.
Changes to materials and shader nodes
Changes the values used for shaders can be made in real time and update all connected nodes. However, adding new shaders, links or materials is not currently supported. Basically adding or linking anything is not supported, but changing existing materials or shaders is where those changes don't involve making or deleting node links or adding/deleting new nodes.
New edits coming soon
Rather than just add more of blender's operations willy nilly, please get in touch with us and tell us what would benefit you. With enough demand from users we put our development efforts towards the most requested features. You can easily do this by creating a post in our forum section - "Future Features". Posts that are getting lots of likes will get a higher priority for getting worked on :D.