AFAIK, this feature is not available in EPDM out of the box... It would certainly be possible with some custom programming, though. I would suggest you look up wlmservices.net
Not sure if you can set an expiration on a workflow state, but something related that might give you some ideas:
A notification deadline can be configured by setting a folder deadline where the file related to that notification is located - RMB Folder > Properties
I have had a chance to dig into this and how to find the variables storing those dates, but I'm sure they're in the database somewhere and can be reported on at least. If they are true variables, then you should be able to call them up in the workflow and pass them through an automatic transition that checks for the time lapsed. It would be similar to a parallel voting workflow that checks for 2 out of 3 Yes votes to allow transition to pass it. If I can dig this all up, I'll repost with some ideas.