Hi developeruspcase,
The basic included sketch with the MKR GSM 1400, which I've used to upload data to a website, runs once only, and then includes a for loop which ensures that the device does nothing after running once.
How has your sketch been configured to run multiple times?
Are you able to give us some help in troubleshooting your sketch by either sharing the sketch you use and the output from it if it does output to standard out. If you can share it, please use the Included code format markup to make it easier to read.
That's probably the best way of troubleshooting is to have the serial monitor open and include some print lines at key places within your sketch to demonstrate to yourself what your sketch is doing or running when it stops working.