How do I delete an app and re-download?

Delete the application from your device. Press down on the icon until all your icons start shaking. An X should appear on the top corner of the icon. Press the X, and you will be prompted to delete.
Re-download the application with the same iTunes login, and you will not have to purchase it again. See:http://support.apple.com/kb/HT2519.
Please restart your device after re-downloading. See the “restart” section below:
iPhone: http://www.apple.com/support/iphone/troubleshooting/phone/#
iPod touch: http://www.apple.com/support/ipodtouch/assistant/itunes/
iPad: http://www.apple.com/support/ipad/assistant/itunes/
Android powered devices http://support.google.com/googleplay/bin/answer.py?hl=en-CA&answer=2521768