If you wish to read data continuously you have 2 options
1. Wrap the above code in a loop that continually re-reads the data after a delay (at least 15 seconds, possibly more depending on your data).
2. If you have an internet-accessible device set it up as a HTTP server and set up a thingspeak react to push the data out to your device. This will (obviously) require much different code to the above.
Unfortunately, no matter how nicely everyone asks, thingspeak does not yet support MQTT or similar pub/sub protocols that would make this task very easy.