The playlists are in the database, so you need to execute some sql using sqlite.
bash-3.2# sqlite3 /opt/var/mt-daapd/songs3.db
SQLite version 3.4.1
Enter ".help" for instructions
sqlite> .headers ON
sqlite> select * from playlists;
id|title|type|items|query|db_timestamp|path|idx
1|Library|1|2686|1|0||0
3|Muse - Black Holes & Revelations|1|11|artist = "Muse" AND album includes "Black"|0||0
4|Prince - Planet Earth|1|10|artist = "Prince" and album ="Planet Earth"|0||0
5|Moby - Play|1|18|artist="Moby" and album="Play"|0||0
6|Jamelia - Thank You|1|14|artist="Jamelia" and album="Thank You"|0||0
7|Coldplay - X & Y|1|13|artist="Coldplay" and album="X & Y"|0||0
8|KT Tunstall - Eye to the telescope|1|12|artist="KT Tunstall" and album="Eye to the Telescope"|0||0
10|Jack Johnson|1|15|artist="Jack Johnson"|0||0
11|Lily Allen - Alright Still|1|11|Artist = "Lily Allen" and album = "Alright, S
till"|0||0
12|Shaggy|1|14|artist="Shaggy"|0||0
14|The Rolling Stone Magazines 500 Greatest Songs Of All Time|1|501|album includes "The Rolling Stone Magazines 500 Greatest Songs Of All Time"|0||0
16|podcast|2|13||1194509883|/share/hdd/data/public/mp3/podcasts/podcast.m3u|0
sqlite>You can then issue an update set query=’xxxxx’ where id=x