[Feature Request] Allow repeat notifications

[dummycaterpillar]

For example, I set low battery level as 40. The app does notify me at 40 or slightly below. But sometimes, I wasn't around my phone when it sounded, so I missed it.

Much more important to have repeat notifications for the high level, because I usually don't use my phone while it's charging.

The notification does happen again tho when I open the app while charging above high level/discharging below low level, after the first notification has sounded.