Usually if i find myself unable to update apps, i'll try to do hard reset. Hard reset is when i press both power n home button for 10 seconds until the ipad first ask if i want to close ( which i ignore, keep pressing both buttons), goes dark and then the apple icon appear and i'll let go of the buttons. It'll take some time for the ipad to power up but you'll not loose any apps and then i'll try to update afterward. it works for me..
Version 1.6 update