Spore saves an automatic backup of your galaxy (including all saved games). If you have not already opened your saved game, you can try to restore this backup.
First, make a copy of the entire SPORE folder, located at C:\Users\{your windows username}\AppData\Roaming\SPORE
This copy is very important, as if anything goes wrong when doing this, you could lose all of your saved games, as well as everything in your Sporepedia.
Then, in the original SPORE folder, go into the Games folder. There should be two folders, one called Game0, one called Game0.old. Game0 represents your galaxy, and Game0.old is the backup copy.
Copy all the files from Game0.old into Game0, replacing the files already in Game0.
Launch your game, and see if that fixes the issue.
If that does not fix it, you may be out of luck. I'm not aware of any way to change the creations manually... it may be possible by directly modifying the files using modding tools, but there is no way to do it in the game itself.