Cant reinstall bought ipad app

Yesterday I bought iCab mobile for my iPad 10.5 Pro. However, I was having all sorts of problems with it so I decided after doing a hard reset of my ipad to uninstall and reinstall. However, now when I go into the app store it wants to charge me again. I have contacted the developer about the technical issues and searched apple for reinstalling applications to no avail. Can anybody tell me how to get my app back please. I know that ¥240 might not be that much but when the soft doesnt work too well at the moment I am a little hesitant. Would like to get the app back and wait on the developer to solve the technical problem.

Sabina