Update json in assets for production (getting data to app for offline experience)

Hello, I have a service which loads some json for data driven user experience

    this.http.get('assets/json/somedataset.json')
      .map(res => res.json())
      .subscribe(data => ...);

The nature of my app is that the government will update data represented in somedataset.json semi regularly and I want to give this data to my users. The reason I am not just loading this data from the web is because this app will need to operate “offline” most of the time due to reception issues.

What would the prescribed solution be to get this new data?