[#4604] Add a method and rake task to clear and update all TimeEntry cost caches

lib/tasks/cache.rake

@@ -1,8 +1,13 @@
 namespace :rate_plugin do
   namespace :cache do
-    desc "Update Time Entry cost caches"
+    desc "Update Time Entry cost caches for Time Entries without a cost"
     task :update_cost_cache => :environment do
       Rate.update_all_time_entries_with_missing_cost
     end
+
+    desc "Clear and update all Time Entry cost caches"
+    task :refresh_cost_cache => :environment do
+      Rate.update_all_time_entries_to_refresh_cache
+    end
   end
 end