That bike has a threadless stem (stem clamps to the steerer), if all of the spacers are below the stem, it seems your only option to raise the bars further would be a different (greater rise) stem and/or bars with some rise in them.
If there are spacers above the stem, these can be moved below the stem to raise it. You will need to re-set the headset preload and tighten the stem/steerer bolts. This is pretty easy to do.
Don't add more spacers, as you will not be able to properly set the headset preload and you will have less of the stem around the steerer, both of which are dangerous.