The typical way to retrieve saved data is by restoring a backup. This only works if you backup, and if the data is included in the last backup. It is also dependent on how the games are being saved. I have no experiences with Clash of Clans, but I have read where some games don't save their data in the backup. Some games have their own servers that include the saved data, if I am not mistaken.
If you want to try to restore the data by restoring a backup, look here for help.
Restore your iPhone, iPad, or iPod touch from a backup - Apple Support