I thought that was where this might be going :) There should be a function, ClusterInfo. Call
Displayed, you should see PrivateKeyFile. To clear it, type
>> ClusterInfo.setPrivateKeyFile('')
The next time you submit a job, you'll be prompted for the new key file. Alternatively, you could just set it above to the new location and you won't be prompted.
The SLURM scripts are well outdated for R2012a+. I have the updated version in my sandbox, it's just making the time to publish them.