Every frame, do you mean tick? How big is a 'place', are you on a grid? Set position would teleport the enemy, is that what you want or do you want more a bouncing off player type thing, for that you can set the angle to reverse of current angle for a bit then continue at the previous angle. For set position teleporting you have the right idea, just calculate which of the 4 directions it's heading in and you can add or subtract x,y based on the enemy direction.