Is it possible to force a re-calculation of a the "Work" field after updating % allocation of resources in the resource sheet or in the resource names column?
I am using MSP 2013 standard.
I'm guessing you mean to re-assign resources at a different assignment units after you change the resource's max units?
If so, not automatically. However, you can quickly replace resources with the same resources at a different assignment value.
For tasks designated as Fixed Units, once there is a value for Work and a value for Duration, MS-Project cannot tell whether you want to keep work the same and adjust duration, or keep duration the same and adjust work.
You could try designating the tasks as either Fixed Work or Fixed Duration, depending on your local needs...