As Ken suggested, there is a wide breadth of mobile offerings and although there are some great "mobile only" funds, each investor / fund has their own thesis that makes them interested in some but disinterested in others.
Also, if your revenue generating, you should seriously consider bootstrapping further. Revenue is treated very strangely in early-stage investing and *might* work against you.
AngelList is a great way to research investors but not effective in actually connecting with them.
Find investors who you are confident will be passionate about what you're doing based on prior job experience or what you know they are investing in.
Happy to talk in a call to help explain this further if you need more clarity.
First you need to do your research and think what is your strategy to approach them. You can find a trick I wrote here:
Apart from this, you could use Mattermark intelligence tool to find investors that have funded similar companies. (Its free for 30 days) Hope this helped :)
What kind of app is it and how are you measuring ARPU? Typically ARPU is average revenue per user per month. Depending on the type of app or game you are, there is a different standard. For example, casual mobile games tend to have $1-$2 ARPU while mid-core games like Clash of Clans has $8 ARPU.