Swype KB App is asking me to pay again after my device swap from Apple.

I recently got my iPhone 5 swapped by Apple for a new device. It was replaced due to faulty power button as per the quality program from apple. After that, i am not able to restore my SWYPE KB app. instead it is asking me to pay again. I reached out to SWYPE App support and they inturn asked me to talk to Apple Support. How can i restore my purchase or should i pay again? (All my other paid apps are available for download from cloud.)