Collision Detection question

I've set up my own "click to move" navigation script that uses iTween to allow the player to place a marker and then move to that position. The script does what I want it to do but I'm having issues with collision detection.

Basically, at the moment, I have set up collision models/primitives that triggers OnTriggerEnter the iTween.Stop(gameObject); function on the player. This works as far as stopping the player when they hit the collision box once. However, if they try moving into the collision model again they pass right through it.

I can kind of see the issue here as when the player clicks to move into a collision model it doesn't get a chance to register the OnTriggerEnter.

Is there a better way of approaching this problem as I'm a bit stumped as to what will make it work properly?