Okay, so I found 2 ways you can get the big probe back. The first one being to load an old save that has it. However, if you're like me and can't do that, there is another way. However, this second method requires an android device so not all of you will be able to do it. First, make a save with a probe in it. Now, you'll want to go to a file manager (I suggest ES File Explorer) and go to storage/emulated/0/android/data/com.StefMorojna.SpaceflightSimulator/files/saving/blueprints, and now you just have to find the save, open it in a text editor, and rename the Probe part to Big Probe, because the big probe is technically still in the game. You could also change the size of it, but that'll go away if you try to move the probe. Here are some screenshots to show that it works.
And Voila! You have the big probe now! Hope this helps!
And Voila! You have the big probe now! Hope this helps!