If you want to "raise more money", you could add more advanced features and add in-app purchases for them. Statistically, about 5% of app users pay for in app purchases (but obviously depends on what features you add). Alternatively, add advertisements, or just use the existing income you're already getting to work on your next app.
In terms of getting investment:
If you coded the app yourself, and you're getting >$10k from it each week, sounds like you can continue to develop it, and anything else, without any need to give up equity for an investment. Meanwhile, if you only made $10k the first week, and now aren't making anything off of it, you're not going to get investment.
If you'd like to go over it in more detail, with regard to the specifics of your app let me know,
Congrats, that is quite an accomplishment. You could probably get some angel or VC interest, depending on how well your app scales. At some point, you will be able to get loans based on your income stream. It also depends on how much you are looking for (and need). You already have at least $7000 coming to you.
At this point, you shouldn't focus on fundraising, mostly because will always take 3-4 months or more, except you are fundraising in San Francisco or Boston.
Instead, you should try to get your app featured by Apple, which will give you 100,000 paid downloads in a week, at which point you don't need any stupid investors who are only interested in making money and not buidling a successful product. ;)
This should be possible if you have a good app and if you know what Apple is looking for.