I have 2 solutions I use: join a group where I am motivated by the energy of others or set a new non-numerical goal (ie I want to bike this event, or I want to handle that hilly ride.) In doing that, I keep myself on my bike.
Additionally, I started using bikes more (and obtained more bikes....but who can gripe about that?) so now I mountain bike, commute, and do utility biking. I participate in local fun rides. When I get back down to my goal weight, I intend to take the advice ofa guy who lost over 250lbs; I will track at least one week out of every month, and my worst two days of each week. That means I will be tracking 12 days a month..less than half. I also keep dragging more friends into biking, which keeps up positive pressure to bike. I went from solo biking to group biking to having my own group of half a dozen friends for regular rides.