Hey there,
Thanks for reaching out to us; sorry for your experience with the Creative Cloud Express. This shouldn't be happening. The project autosaves in real time whenever it is worked upon.
Would you mind telling us which browser you were working on and since when were you facing this issue? We'd also like to know if this happens with all the projects or specific ones?
Note: As a workaround, you can create duplicates of your final project to avoid redesigning from scratch.
We are happy to help, just need some more info.
Thanks,
Amitej