App Startups: Tips for Retention?

Hi guys :)

I've been building an app called Keys, www.thekeysapp.com. We think of it as a superpower for dating apps, allowing users to select any curated phrase from our keyboard for any app.

I've been trying to boost our retention metrics over a period of a couple of weeks to encourage investors to get on board. Any tips or suggestions on how I can raise retention on my app?