Hi,
For example, if your app it's deployed with this context path /yourapp and you place a resource file with your json model in /yourapp/resources/oNewData, you could load replacing hardcoded model in view with this sentence:
var newModel = new sap.ui.model.json.JSONModel();
newModel.loadData("/yourapp/resources/oNewData", '', false); //false = load sync model
//data process
Kind regards!