How do I motivate my ostrich workers?

I’m the HR manager of a medium-sized company. I’ve been here for five years and, up until about 12 months ago, the organisation was characterised by its many highly driven individuals. The company was growing fast and there was always a great appetite for people to develop their skill sets and help move the company forward.As the downturn has started to have an impact, however, a lot of workers have begun to stagnate as the company’s growth has slowed. Whereas previously everyone was pushing for promotion and eager to move up the ladder, opportunities have now dried up. The tendency among our people now is to stick their heads in the sand, get on with their jobs quietly and simply try to avoid redundancy by not rocking the boat. How do I re-energise my people and bring back the sort of ambition and hunger for development that helped the company succeed in recent years?