Most of the Autodesk programs have a built in feature that allows you to see if an update/service pack/maintenance release or hotfix is available for the program you are running.
From within Architecture click the little down arrow in the upper right corner and it will fly down a menu to let you know if a maintenance update or hotfix is available for your program. Click the "Product Update Available" link as shown in the image below.
It will bring up a web browser window. Click the "Update" button
It will start the download and then kick off the install, I'd close out of AutoCAD Architecture at this point.
the install progress window.
Note: if the installer needs to update any Operating System files or 3rd party applications ( like Internet Explorer) you may receive a window indicating that you can close them and continue or that you may (should) reboot after the install has finished.
I reboot after installing or uninstalling an Autodesk program or its service pack.
So I selected the "Do not close..." and clicked Ok.
Now just Reboot and launch Architecture 2014!
Sometimes, for security reasons, you will be unable to download and install using this method. Your Communication Center may or may not give you an error and sometimes it won't show you if an update is available.
If your Communication Center is turned off or blocked, then you can go to the Autodesk website and download/install it manually.
Click "Browse Downloads"
Click the service pack you need, since we're doing Architecture 2014 it's the AutoCAD Architecture 2014 service pack 1.
Click to download the appropriate service pack and PLEASE do not forget to check the Readme! I'd even read the text above the links to download. Some of the Autodesk program still require you to download and install service pack 1 before service pack 2. Others have service pack 1 included in service pack 2 so there's only one download & install needed.
Then double click the .exe file to install the program.