Updating SLA time assertion for all the test cases in a project

Hi,

My current project structure look like this .. 

Project 

   -- Test suite 1

         -- 10 Test cases

   -- Test suite 2

          -- 20 Test cases

....

I had given assertion as 2sec for all the 250 test cases, I would like to know if I can change the assertion value for all test cases using a groovy script to 5sec instead of changing assertion value for each individual test case.

Thanks,

Lokesh