I deleted an app, which I paid for? Do I have to pay again when I redownload it?

I downloaded Countdown + and then upgraded so there would be no adds and so I would recieve the extra features (backgrounds etc). The upgrade was $1.99. I deleted the app, however, on my phone, because it continually crashed. They fixed the issue so I reinstalled the app, however when I opened it, it was only the lite version and not the upgraded version which I paid for. How can I get the upgraded version back without repurchasing it?

Thanks!