how to transfer game data from one google account to another??

I have a tablet that I have given to my wife.. She now has games saved under my google account..
I want to delete my account from the tablet and add her account.. but she says she has been playing the games for months and don't want to start over.. how can I transfer her game data (which is saved to my google account) to her google account??

also the tablet is not rooted..