1. Focus on circling away and lateral movement, obviously. And TDD more (which actually looked much improved last time, but it could still be better.) Also, work on escapes from the clinch.
2. Stay off the cage AT ALL COSTS. It's crazy, but JDS actually got hurt worse on the cage in Fight III than he did on the ground in Fight II.
3. Abandon any thoughts of focusing on trying to get a highlight reel overhand right KO. The blows he hit and slightly hurt Cain with last time were lead hooks and short elbows in close range; increasing the power of these blows and ensuring he can land enough of them to hurt Cain should be his #1 priority, hence...
4. Start training to fight southpaw, like Machida and Anderson do. Keep his strong, coordinated side forward to help him fend off TDs. Focus on training right-handed jabs, right hooks, right uppercuts, or lead right elbows. As for the left hand, train the straight left to the head and body mostly; an overhand or uppercut with the rear hand leaves him too vulnerable and open to getting taken down or getting caught standing.
Mostly though, I think he needs to shake up his striking approach and strategy. He can't obsess with getting another perfect 1 punch KO. He has to focus on landing a number of strong blows early in the fight to get Cain's respect or slow him down, and only then will he get a chance at another KO.
"Do you believe you're still as fast as you were, even 10 years ago?" -Michael "The Voice" Schiavello
"Maybe faster..." Steven Seagal