On the Apple device, the Exchange account password (used by Traveler) is not always retained after the iOS upgrade.
Currently there is no resolution to prevent the user from having to reenter their password (as detailed in the solution listed below). However, the following IBM Feature Request has been opened for further investigation: RSSN-8K2GWU
In most of these cases, the problem can be fixed by simply reentering the password for the Lotus Notes Traveler account (Exchange Profile) on the device.
Here are the steps for entering the password on the device:
1) Select Settings
2) Select Mail, Contacts, Calendars
3) Select the correct Domino mail account
4) Select Account
5) Enter the correct Password and select Done
Information above from this TN