For removing lanolin from fleeces (I'm a handspinner), I use plain old Dawn dishwasing detergent. I forget what the ingredient is, but it's a less concentrated version of what's used for commercial scouring of wool.
Anyhow, throw those shirts in a hot hot wash with a good squirt of Dawn & let 'em sit for 15 minutes or so. Rinse well & dry. Should do the trick. If it doesn't, then I'm out of ideas.