AS3 blur filter help

Hi, I am fairly new to ActionScript three and I encountered a problem while creating a simple painting application -- I was adding a blur slider to allow the lines to be blurry whenever someone draws, but what I did was make all lines already drawn become blurry. 

blurSlider.addEventListener(Event.CHANGE, changeBlurFilter);
function changeBlurFilter (SliderEvent):void {  
  
var myFilter:BitmapFilter = new BlurFilter(blurSlider.value,blurSlider.value, BitmapFilterQuality.LOW);
var lineFilters:Array = new Array();
lineFilters.push(myFilter);
board.filters = lineFilters;
          }

This is the code currently. board is the canvas that can be drawn on.  So as of now everytime the blur slider is changed all marks on the board become blurry -- which is not the intention. Is there a way to add the filter to something like

board.graphics.lineStyle.(sizeSlider.value, selectedColor, alphaSlider.value).filters = lineFilters;

Of course this does not work, but this would change the linestyle to become blurry. Is there another way to do this?

Thanks a lot in advanced