Reregister device under same name in zone

Hi!
I have one Windows device "lost" registering info for zone, I mean, I get error about wrong credentials. I wondering can I reregister this device and associate it with existing (for same device) object in zone? When I'm trying to use zac and rereg I get error -- already existing (registered), when I use reg I get error -- -34, invalid device auth info.
Any ideas? I want to keep existing device info in zone.
Probably is lost correct id info in file DeviceData. Totally my fault.
More thanks, Alar.