You could try motivating your team by convincing them that the best way to prepare for their next job is by doing well at their current job.

For instance you could give them tasks that would give them the opportunity to learn valuable and marketable new skills. Maybe they want the opportunity to get some hands-on job experience with Cisco, Citrix, Linux, Exchange, or whatever. If you let them spend part of the day getting valuable new skills that will help them land a job after the next round of layoffs then they would probably feel better coming to work everyday and have a more positive attitude. They would also be more likely to complete the other tasks you give them.