Some research showed that other people had this problem as well.
Apparently, this is a bug that is caused by the current iteration of the ICCup launcher.
Unlike previous versions, the launcher no longer re-adds the registry entry for ICCup every time you start it. As a result, anytime you access a regular battle.net gateway (such as USEast) Blizzard removes the ICCup entry and you have to go back to ICCup.com and get the registry entry.
If you are interested in doing this manually, the following steps should suffice just know that anytime you manually edit your registry, there can be dire consequences if you do it wrong.
Manual Registry Edit:
- type 'regedit' into the start menu's 'Run' dialog or directly into the search for windows Vista and beyond.
navigate to "HKEY_CURRENT_USER -> Software -> Battle.net -> Configuration"
open the Battle.net Gateways key
add the following lines to the bottom of the file then save and close it. (Note: the format is always gateway address, time difference and then server name.)
Upon restart, you should have iCCup at the bottom again.
However this change will revert anytime you connect to a Blizzard gateway.
credit to: sGs.DNH
The original, source of this, including another option in case this fix doesn't work can be found at: