You could create another coin instance at location (random(LayoutWidth), random(LayoutHeight)) when the player collides with a coin. Presumely, this should be after when you would do the action destroy coin in the collision event.
But the random coordinate above will sometimes create the coin at undesirable locations such as at the edge of the layout. This could make the coin appearing only partially on the layout. If you don't like this, you will want to add the size of the coin into account, so:
Assuming the hotspot of the coin is at the center,
coinWidth/2 + random(LayoutWidth - coinWidth),
coinHeight/2 + random(LayoutHeight - coinHeight)