Not able to use the same model from previous page

In my first page, I am getting the model like :

model:function(){
        return this.get('store').findAll('offer').then(function(data){
            return data.get('firstObject');
        });
    },

when user click on next button, I am taking them in to next page. where i require the updated model from previous page. so I am trying to use the same model as what i updated like:

model:function(){
        var model = this.modelFor('HK.cs2i.cs2i.purchase.purchaseDetails');
        console.log('model is', model);
        return model;
    },

But on the console, I am getting the mode as undefied. is it require to do any workarounds or something else to access the previous mode?

any one help me here?