Is there anyway to recover a deleted save game slot if you delete within the AGS game?
No, it deletes actual file.
You can only do this by getting specialised software that lets you access deleted files, so you can remove the flag that says the computer is allowed to overwrite it.
But that's complicated, and might require a bit of luck, since your computer might have already overwritten it.
*reminiscences to when undelete was a OS command... (roll)