By far the best solution is to just get another 4g plan identical to the one you have now. If your device supports it you can swap sim card every 15 days and stop worrying about it. If not you'd have to just swap each device out every 15 days. Not the most elegant solution but it works - is easy to manage and won't cost you an arm and a leg.
This is what I have been doing as a work-around......