You can do a dbimpexp from Lync 2010 to a xml file. Lync 2013 does not use dbimpexp more, but have a native import-csuserdata.

These two commands does not use the same fileformat – this is where convert-csuserdata can help. This command convert from dbimpexp xml format to the zip(xml) format used by import-csuserdata.

convert-csuserdata -PoolFqdn Lyncpool.test.local -InputFile FromLync2010.xml -OutFile ToLync2013.zip -TargetVersion Current

TargetVersion can be “Current” or “Lync2010” so this command can be used to convert between the two Versions.