Code:
### This set of queries changes the respawn times for the following zones ###
UPDATE spawn2 SET respawntime = 1800 WHERE respawntime < 1800 and zone = 'sebilis';
UPDATE spawn2 SET respawntime = 1800 WHERE respawntime < 1800 and zone = 'karnor';
UPDATE spawn2 SET respawntime = 1800 WHERE respawntime < 1800 and zone = 'velketor';
UPDATE spawn2 SET respawntime = 1800 WHERE respawntime < 1800 and zone = 'skyshrine';
UPDATE spawn2 SET respawntime = 1800 WHERE respawntime < 1800 and zone = 'kael';
UPDATE spawn2 SET respawntime = 1800 WHERE respawntime < 1800 and zone = 'ssratemple';
UPDATE spawn2 SET respawntime = 7200 WHERE respawntime < 7200 and zone = 'vexthal';
UPDATE spawn2 SET respawntime = 1800 WHERE respawntime < 1800 and zone = 'akheva';
UPDATE spawn2 SET respawntime = 1800 WHERE respawntime < 1800 and zone = 'chardok';
UPDATE spawn2 SET respawntime = 1800 WHERE respawntime < 1800 and zone = 'sseru';
UPDATE spawn2 SET respawntime = 1800 WHERE respawntime < 1800 and zone = 'soldungb';
UPDATE spawn2 SET respawntime = 1800 WHERE respawntime < 1800 and zone = 'permafrost';
UPDATE spawn2 SET respawntime = 1800 WHERE respawntime < 1800 and zone = 'kedge';
UPDATE spawn2 SET respawntime = 1800 WHERE respawntime < 1800 and zone = 'hole';
UPDATE spawn2 SET respawntime = 1800 WHERE respawntime < 1800 and zone = 'citymist';
UPDATE spawn2 SET respawntime = 900 WHERE respawntime < 900 and zone = 'unrest';
UPDATE spawn2 SET respawntime = 900 WHERE respawntime < 900 and zone = 'warrens';
UPDATE spawn2 SET respawntime = 900 WHERE respawntime < 900 and zone = 'soldunga';
UPDATE spawn2 SET respawntime = 900 WHERE respawntime < 900 and zone = 'runnyeye';
UPDATE spawn2 SET respawntime = 900 WHERE respawntime < 900 and zone = 'oot';
Here's an example. The respawn times are in seconds, so determine what you'd like them to be. These are written in a way so as not to interfere with named spawns, so only touch spawn timers that are
below or equal to the one you're setting.
Hope this helps, good luck =)