I have a page that contains a user control within an update panel. $(document).ready(function() ) { is called and executes the code correctly when the page firs
I've run into this a while ago, as El Ronnoco said, it has to go with the DOM not being reloaded. However you can simply change
$(document).ready(function() {
to
Sys.Application.add_load(function() {
This will force it to run on every postback.
You can use function pageLoad() as well, but you can only have one pageLoad function, whereas with Sys.Application.add_load, you can add as many handlers as you wish.