Observer not working on page back / front button use

In my component I have a observer which is setting the max amount as a value. when I load the page it sets and all are fine.

In case if I use back of the browser and come again to page, I am getting default select value instead of the sorted one.

how can i force my observer to re-calculate on back transitions? ( back / front button )

here is my code :

onValueChange:Ember.observer('selectedCreditCard.requestAmount', function(){

        var value = Number(this.get('selectedCreditCard.requestAmount'));
        var that = this;


this.get("selectedCreditCard.tenureDetails").forEach(function(item,index){

            if(value >= Number(item.min) && value <= Number(item.max)){

                console.log("item.tenures", JSON.parse(JSON.stringify(item)) );

                that.set('selectedCreditCard.matchingTenure', item.tenures );
                that.set('selectedCreditCard.handlingFee', item.handlingFee );
                that.set('selectedCreditCard.minAmount', 1500 );
//first time works. on page shuffle not works!!
                that.set('selectedCreditCard.selectedTenure', 
                    that.get('selectedCreditCard.matchingTenure').get('lastObject') );//setting value
//works based on above settings. so fails!!
                that.monthlyInstalment();
            }
        })

    }),