I have purchased Asphalt 7 but I can't download it without paying after update to iOS 7

Hi! I bought Asphalt 7:Heat about 3 months ago. I've downloaded it without any problem. But 2 days ago, I deleted it and i updated my ipad to ios 7. I tried to download asphalt 7 but i must pay 1 dollar to download it. I can't download it free. Please help me.