You can either directly re-download them on the iPad (http://support.apple.com/kb/HT2519), or select the apps that you want to sync to the iPad on the device's Apps tab when connected to your computer's iTunes - select the iPad device on the left-hand side of iTunes and then on the right-hand side select the Apps tab, tick the apps that you want and press sync.
If you want the apps (including their settings/content) back as they were on your iPad then you can try restoring from your backup : http://support.apple.com/kb/HT4079 (this will restore the whole iPad) - if a backup was last made after the apps were removed from the iPad then you won't be able to restore their content/settings (as the backup won't contain them).
I want to make sure I do this correctly. I just updated to OS version 5.0 and yes, my apps are on iTunes on my PC, but they did not go back onto the iPad after the update. Not even after the post-update reboot/restore while linked (I think the "restore" vernacular is too broad here). I want to get all my apps back on the iPad, but would actively restoring the iPad revert it back to 4.3.3??
Every time I sync my iPad and update the software I end up regretting it. Takes so long repeating everything only for it not to end up the way I wanted it. I am tempted to just manually download the apps again directly from the iPad, one by one. All 252 of them.