We have seen how to upgrade iPad to iOS 5 and the steps required before installing the software. If you had transferred your purchased iPad apps to your computer then it would be automatically copied back after the upgrade. But in case if the apps are missing after the upgrade then you can reinstall them by following the manual steps.
Launch App Store and click the Purchased icon available at the bottom of the store app. This would display the following Apps screen.
Navigate to Not On This iPad tab and choose app that needs to installed. Tap the download icon available for the app and this should install it on your iPad. This is not the best solution if you want to install many apps but by this way you can recover any missing apps after iOS 5 upgrade.