if you are showing the score (passing the value to a text object) you can add by taking the value from the text object, add the score just made to it, and pass that new value back into the text object. Don’t try and pass it back into the same text object xpresso node make a copy or just drag in the text object to the xpresso window again…
so in xpresso it’s
Text Object Node -> Math -> Text Object Node
score node ———-^