Although the Google Play Store version of OpenCV Manager hasn't been updated since OpenCV 3.0.0, I see new builds in the apk folder of the OpenCV Android 3.2.0 release (from http://opencv.org/downloads.html). Choose the APK that matches your Android device's architecture, and sideload it using ADB. For example, if you are using an armeabi-v7a device, run this in the command prompt:
adb install OpenCV_3.2.0_Manager_3.20_armeabi-v7a.apk
[Edit 1] Of course, if you're concerned about easily distributing your app to other people, you shouldn't depend on a version of OpenCV Manager that has to be sideloaded. However, if your app is just for your use or internal organizational use, this might be fine.
[Edit 2] I've opened an issue at https://github.com/opencv/opencv/issues/8120 to request that the latest builds be published to Google Play Store.