How do I update a variable within $timeout?

I have a function within a $timeout to which I want to pass a variable called 'renderlevel'.

Later I want to update 'renderlevel' and for it to update within $timeout. Can someone advise me how to do this? 

var renderlevel = 0.2;

$timeout(function() {
 for (i = 0; i < rLen; i++) {
 $scope.view.wdg[renComponents[i]]['texture'] = "app/resources/Uploaded/MyImage.jpg?name=tex0&edge=repeat";
 $scope.view.wdg[renComponents[i]]['shader'] = "reflect;mixer f " + renderlevel;
 }
} ,50);

//Later...
renderlevel = 0.5;
//Update timeout??

Update: this is a lot simpler than I realised. This is my basic but functional solution:

//SHADER - runs at startup
$timeout(function() {
 for (i = 0; i < rLen; i++) {
 $scope.view.wdg[renComponents[i]]['texture'] = "app/resources/Uploaded/MyImage.jpg?name=tex0&edge=repeat";
 $scope.view.wdg[renComponents[i]]['shader'] = "reflect;mixer f " + renderlevel;
 }
} ,50);

//SHADER UPDATE - runs when called
$scope.shaderUpdate = function(){
 $timeout(function() {
 for (i = 0; i < rLen; i++) {
 $scope.view.wdg[renComponents[i]]['texture'] = "app/resources/Uploaded/MyImage.jpg?name=tex0&edge=repeat";
 $scope.view.wdg[renComponents[i]]['shader'] = "reflect;mixer f " + renderlevel;
 }
 } ,50);
}

//SHADER AMOUNT
$scope.shaderLevel = function(){
 renderlevel = 0.5; 
 $scope.shaderUpdate();
}