Vibration Notifier offers a solution to this scenario: When you have a missed call, unread SMS or any other event*, the app keeps vibrating every X minutes for Y times or until you turn on the display of your device.
Troubleshooting: The app won't beep if your device is set to silent mode etc. Please note that the app does not change the vibration setting of the other apps, it will only do additional vibrations/beeps if you don't turn on your display before!
An optional feature is available as an in-app purchase (0.99 EUR) with which you'll get these repeating vibrations on your Android Wear smartwatch!
* all apps which notify you about new events by showing a notification in the Android status bar are supported, like WhatsApp, GoogleTalk, Twitter, facebook, etc. Note that this require access to your notification bar
If the app doesn't work: Please check if your device manufacturer implemented a "feature" which prevents apps from running, like Samsung's "Battery Optimizer", Sony's "Stamina", Huawei's "Protected Apps" or anything like that.
Silent hours: Please note that when you set up a silent hours interval in the app, only Vibration Notifier itself won't vibrate or beep. It does not mute other apps so if you receive a new mail, your Gmail app might still beep!
Initial vibration: The app vibrates/beeps after the time set in the app - it does not vibrate/beep immediatelly when you receive a notification (the notifying app is responsible for that vibration)! However, there is an option in the app to get the initial vibration on the connected Android Wear device.
This app uses Accessibility services. The accessibility service is necessary on Android versions prior to 4.3 to be notified about new notifications. The accessilibty service is not needed on newer versions of Android.
VIBRATE - obviously necessary to enable the "vibrate every X min" feature
READ_PHONE_STATE - needed to detect missed calls
RECEIVE_SMS & READ_SMS - needed to detect unread SMS
WAKE_LOCK - seems like this is needed on some device to avoid infinite vibrating
READ_CALL_LOG & READ_CONTACTS - needed to differentiate between missed & rejected calls
READ_CONTENT_PROVIDER & GET_ACCOUNTS - necessary for new method to get unread Gmails
WRITE_EXTERNAL_STORAGE - Android Wear communication