Keychain keeps getting overwritten by iCloud

I mistakenly removed a lot of passwords from my keychain via Safari. These were in the iCloud Keychain and so presumably were removed from the iCloud Keychain at that point. I then restored an earlier copy of the keychain from a Time Machine backup, however iCloud keeps overwriting it so the passwords disappear.

How do I get the passwords back into iCloud Keychain? There appears to be no way to restore previous versions of the keychain within iCloud itself.