This original app has 3000 new users each month. Be the first who buys this code (or you can buy the app with transfer).
So, first what shall you do - it's implement in-purchase. And earn money by in-purchase or limited demo-period. You can let users use only English, and sell each additional language for 1 dollar. Or let users use all languages for 3 days, after which all languages except of English would be unavailable until users pay to open certain. Say, dollar for open 1 language, or 3 for open 8, or 5 to open all.
How to make it viral. Allow users to open additional languages after sharing a link to a friend. Seperately allow to unlock history of search after sharing the link and so on. So, each of daily users will bring you 3 new users.
Also, you can easily add 4 more languages to the app, and I'll help you with that.
Also you must redesign the app. Let user to unblock admod through in-purchase too.
Also, as I said, there are 4 levels of quality for each language. You can open them after in-purchase too, or let user use it for 3 days and after that block until they purchase all levels.
There are also a few bugs, which you must fix. And generally you must care the app, publishing updates. I have a few ideas about interface, and I can help you with that through advices. Something, like menu of the app, is out of date, cuz was created 3 years ago.
As for now the lite version suggests to buy full, which is not effectively.
So, you can earn, selling new languages, selling quality levels, selling robotic feature, sellling blocking of the ads and on the ads.
So, it'll take two weeks tops to embody all suggestions and you will start to earn after that and increase it. Also I'll help with promotion through social networks. BTW, about promotion through SN: implement feature to send found rhymes to Twitter and so on, so that there were the link to the app. I have way more suggestions, which I will share with the buyer. Including the great possibility to earn money, which I was told by one of the market experts - offer this rhyming service to some dating sites/apps. Their clients will be happy to send poems each other. If you could offer this project to them and integrate it, it would be your jack pot. Cuz there are no apps with such a quantity of languages in the world except of this.
Also I can sell you iOS codes for this app. Text me for detailes.
Also you can buy the whole app with transfer (for Android or iOS separately or both). All 7 apps from this family has about 400k downloads and 30k active users. Text me for detailes.
Note: I'm not programmer. I was author of this project and managed its development as the Project Manager. So I can't help with integration, but my former web-programmer (who wasn't engaged in this app development and who hasn't skills in developing apps at all) removed the app from one server to another within 3 days.
Note: you can use my server till February, 2017. You must move your service to your own server before Februrary.