As mentioned you already have a high deductible plan, but I would look at moving to an H.R.A. We moved from an H.S.A to an H.R.A this past year and we have had a very positive reaction. Although we are a small company (150 employees) we had a large amount of people jump from the more expensive PPO plan to the H.R.A. The key to this being successful on our end was great communication from our provider and insurance broker to the employees.
Something else to know, the H.R.A. is particularly expensive the first few months when employees are using the employer paid part of their bridge but we have found the past 6 months to be very inexpensive.
As we also felt the pain of potentially increased insurance last year we moved from a benefit rich PPO plan to one with less benefits; a $500 deducitble, lower co-insurance, etc. While employees didn't like the reduced benefits, those that were interested in the PPO plan did like that there was not a rate increase, and a lot of those employees that didn't really care which plan they were in migrated to the H.R.A which saved the company money.