This should be the way to check whether it is received, however it generates a lot of traffic. But there is an other way, with some latency. If you need to have low latency acknowledgement you should enable automatic replay mac set ar on. This does practically the same as your little script.
The gateway will wait forever for acknowledgement of the mote. The LoRaWAN specification (4.3.1.2) has some, though minimal, information regarding how acknowledgement is sent by a mote (end device). If you don't need the low latency part you should just wait for the next transmission of the mote to confirm the downlink message.