unfortunately you can't. SMS messages are limited to 160 characters due to the current standards. Gosms should only be sending two messages, therefore it looks like a bug in the current version of the app.
You should be able to change a setting to not split messages, but that makes it send the message as MMS (because, as GameDus said, the SMS standard limits the message to 160 characters), but this sounds like something automated so you wouldn't want an MMS message.