I have a user control that contains only a text box and on another form I add this user control dynamically, a user can add the user control many times. I use a session vari
Use the object cache. Add the usercontrol into the cache and retrieve it when you need it.
You can see a nice example of how this works at: ASP.net-Tutorials Cache and Object Cache.
I am also learning asp.net now and found that quite a nice explanation. I also used the Microsoft Library