Reconfiguring AT chatfile, once modem disconnects

Question

Hello I'd like to implement a function in my chatfile, so my modem reboots itself, whenever it hangs. It usually comes back online after the module reboots, but then falls offline again after some time and after 3 echo requests. This reboots my modem:

echo -ne "at#reboot\r" > /dev/ttyACM3

This is my current chat file:

# Connection to the network 
'' AT+CGDCONT=1,"IP","<shared.m2m.ch>" 
# Dial the number. 
OK ATD*99***1# 
# The modem is waiting for the following answer 
CONNECT ''

If this isn't possible, I will need to reprogram our app, that sends the at command, whenever it falls offline.

thanx in advanx