Edit in JSFiddle

<div ng-app="MyApp" ng-controller="MyCtrl">
    <div>
        <label>Write here first (the variable will be shared among the two inputs):</label>
        <input ng-model="obj.prop" type="text" /><br />
    </div>
    <div ng-if="true">
        <label>Write here first (the two input boxes will live indipendently):</label>
        <input ng-model="obj.prop" type="text" /><br />
    </div>
    <a href="#" ng-click="reset()">Reload the demo!</a>
</div>

angular.module('MyApp', []).controller('MyCtrl', function ($scope) {
    $scope.reset = function() {
        window.location.reload();
    };
});