I have a site that has many thousand pages that target individual towns / cities but are essentially duplicate. This used to work fine until recently with the google updates and now the traffic is alot lower than it used too but they still get some traffic.

Question:
Where do I go from here? Making each town or city page unique will be too big a task so I'm thinking of redirecting each of these back to the county level page and make these unique as they're only 100 of them.

The current structure is as follows:
domain.com/county-page/town-or-city-page.htm

Can you recommend this approach?