From a home screen, select Apps (located in the lower-right).
From the Apps tab, select Settings.
From the Personal section, select Backup and reset.
From the Backup and reset section, ensure the appropriate account is selected from the Backup account field then configure the following:
Enabled when a check mark is present.
If data back up is disabled, existing backups are deleted from Google's servers.
Back up my data
Personal data such as WiFi passwords, browser bookmarks, user dictionary, a list of installed Market apps and other customized settings are backed up to Google's servers.
Data and settings are restored to apps utilizing the backup service upon re-installation.