$scope.Model = { items: [] };

scope.onAdd = function(e) {
   items.push({
      // properties
      Label: function(item) { // some code that computes the value of label as the item changes }
   });
};

<div ng-repeat="item in Model.items track by $index">
   <div>{{ item.Label(item) }}</div>
   <div>{{ item.Name }}</div>
</div>

// directive setup
function(scope, element, attributes) {
   var getter = $parse(attributes.ngModel),
       setter = getter.assign,
       data = {};

   // some kind of crazy code to get things from database
   // and assign it to 'data'

   // next, assign the Label() function to each item, since it
   // wouldn't exist right out of the database
   angular.forEach(data.items, function(value, key) {
      value.Label = function(m) { // normal label code // };
   });

   // assign the data with the attached functions to the model
   setter(scope, data);
}

// setup controller code
// setup the model
$scope.Label = function(m) {
   return //{stuff happens with m here};
}

<div ng-repeat="item in Model.items track by $index">
   <div>{{ Label(item) }}</div>
   <div>{{ item.Name }}</div>
</div>