diff --git a/config/config.go b/config/config.go
index 814fb74..b0f10c1 100755
--- a/config/config.go
+++ b/config/config.go
@@ -5,6 +5,7 @@ import (
 	"local/args"
 	"os"
 	"strings"
+	"time"
 )
 
 var (
@@ -15,6 +16,7 @@ var (
 	StorePass string
 	Root      string
 	OAuth     string
+	Loop      time.Duration
 )
 
 func init() {
@@ -34,6 +36,7 @@ func Refresh() {
 	as.Append(args.STRING, "storepass", "pass of store", "")
 	as.Append(args.STRING, "oauth", "url for boauthz", "")
 	as.Append(args.STRING, "root", "root of static files", "./public")
+	as.Append(args.DURATION, "loop", "loop duration for refreshing completed tasks", time.Minute)
 	if err := as.Parse(); err != nil {
 		panic(err)
 	}
@@ -44,5 +47,6 @@ func Refresh() {
 	StoreUser = as.Get("storeuser").GetString()
 	StorePass = as.Get("storepass").GetString()
 	Root = as.Get("root").GetString()
+	Loop = as.Get("loop").GetDuration()
 	OAuth = as.Get("oauth").GetString()
 }
diff --git a/main.go b/main.go
index 9eb6309..f086575 100755
--- a/main.go
+++ b/main.go
@@ -12,6 +12,7 @@ func main() {
 	if err := s.Routes(); err != nil {
 		panic(err)
 	}
+	go s.Async()
 	log.Println("listening on", config.Port)
 	if err := http.ListenAndServe(config.Port, s); err != nil {
 		panic(err)
diff --git a/server/ajax/ajax.go b/server/ajax/ajax.go
index ecdbb7f..fb0cd0f 100755
--- a/server/ajax/ajax.go
+++ b/server/ajax/ajax.go
@@ -3,8 +3,11 @@ package ajax
 import (
 	"local/storage"
 	"local/todo-server/config"
+	"local/todo-server/server/ajax/task"
+	"log"
 	"net/http"
 	"net/url"
+	"time"
 )
 
 type Ajax struct {
@@ -82,3 +85,39 @@ func has(params url.Values, k string) bool {
 	_, ok := params[k]
 	return ok
 }
+
+func (a *Ajax) Async() {
+	c := time.NewTicker(config.Loop)
+	for range c.C {
+		log.Println("loop tasks")
+		if err := a.loopTasks(); err != nil {
+			log.Println("failed to loop tasks", err)
+		}
+	}
+}
+
+func (a *Ajax) loopTasks() error {
+	lists, err := a.storageListLists()
+	if err != nil {
+		return err
+	}
+	for _, list := range lists {
+		tasks, err := a.storageListTasks(list.UUID, func(t *task.Task) bool {
+			return t.Complete
+		})
+		if err != nil {
+			return err
+		}
+		for _, task := range tasks {
+			if !task.Complete || task.Loop == 0 || time.Since(task.Completed) < task.Loop {
+				continue
+			}
+			task.Complete = false
+			task.Completed = time.Time{}
+			if err := a.storageSetTask(list.UUID, task); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}