Let's be clear on that I do not know anything about desktop file. All i assume is you have some script, so all you need to run it is:
chmod +x "/path/to/script.sh" && /path/to/./script.sh
I think most of the crashes on Wazapp that Im using is/was caused by switching of connections from Wifi to 3g and vice versa. Some of this crashes, the UI just hanged without any activity. I tried the script and experienced while it tried to reconnect the hanged Wazapp, it comes to a loop of 'connecting', 'online', 'offline'. Is there anyway to make the script to completely shutdown the app before restart and connect?
BTW, I'm using the dev version. I've able to avoid the hanged Wazapp crash by staying on 3g all the time and completely disabling Wifi connection for it.