Lost Cluster Recovery

Recording MP3 with my handy-dandy 1 gig Xonix watch when loss of battery power terminated the operation. My understanding is the audio data still exists but as lost clusters. I have tried to recover the file but cannot since the file length and file name was never written to the jump drive/watch.

Question is: If I start the watch to record again and then stop the recording, writing file name and file length on the drive to the new file, could I then somehow change the file length to include the data previously written and recover the majority of the file in this way?

The file is pretty important and it would be worth paying someone to do this if it could be successfully done.