Updating existing Index on views

I am building an app on Phonegap and I have a view, i.e.:

sites : {
map : function(doc)
if (doc.type == “site” && doc.created_at && doc.name && doc.geography.country) {
name : doc.name,
country : doc.geography.country

When I need to update any view, for example to add a field, I must remove the complete app and then re-install it, because the view does not update all the existing indexes and shows only the previous view output.
Is there a way to force the indexing of all documents after I make a change to the view?