There are several options. One way is to create a named EventWaitHandle. When project B updates the settings, it sets the event. Project A has a thread that waits on that event. When it gets a notification, it updates from the settings and then resets the event. I have a simple example here: Send message from one running console app to another
That will work if project B stores the new settings somewhere where project A can read them. If you want to do it in memory (i.e. project B doesn't persist the settings), then you need to set up some type of communication between the the two processes. You can set up shared memory using a MemoryMappedFile, in which case you'll still need the event notification.
Or you could set up a Named Pipe with a server stream in project B and a client stream in project A.