Camera Raw as smart object adjustment layer

Hi,

My normal workflow is i have a number of layers and layer masks, working with all the basic stuff. Then i usually copy all layers flatten them to make a smart object layer above all. Open that layer in Camera Raw to make the last finish (color, contrast and grain). Sometimes I want to make an adjustment to one of the layers below and have to redo the camera raw smart object-layer. 

Is there any way I can make that layer "live" So I still can make adjustments below and the smart layer just make the color/contrast adjustments? I've tried making the camera raw layer 50% grey but that doesn't look right.