if you use windows then download the new version, go to C:\Users\<USERNAME>\AppData\LocalLow\Denki\Autonauts amd take take <your world's name>.txt and put it in the Autonauts file, under the app and not in the data.
if you use macOS then you will need to right click (or press with 2 fingers on the trackpad) on the old version, select the second option (Show Package Contents) and then select <your world's name>.txt
put that in a place that you would be able to find it, download the new version, right click on it, select the second option and put <your world's name>.txt BELOW the file called contents, NOT in it.
if you use linux, well, i don't know.
on windows there is a way easier way to do this.
First go into the new version of the game that you downloaded then press escape then click the load button. After you have click on this C: ( should be on the side bar) and find user. Then find your username. Once done find app data then go localLow then Denki then Autonauts. Your save file should be somewhere in there.
