Congrats on your successful slimming program!. Here are a couple of tips that you might not have utilized yet.
Do not feed the dogs in the evening at all. If you feed twice a day, let the last meal be at 4pm or so, and let it be the smallest meal. Then every one out for a walk, or training time.
For your trick training - which btw burns lots of calories, use green beans, or cheerios, or something very low low cal.
For a game of ball fetch, if your house has stairs and their joints are healthy, throw that ball up the stairs!
Beg, stand, sit, is excellent muscle conditioner and burns calories too
Treadmills can work too, if you have one.
Try to find a "playdate" place for Yorkies. Here we have a meet up once per week at different locales.
OUr dogs love the game of "Find the toy". The toy is their reward. They go crazy going up and down the stairs, running around, reaching up to sniff, etc, etc.
Think about a home made obstacle course. Take them through one at a time. Have some low jumps, a balance beam, a teeter, and a tunnel they go through. There is a thread on here, of someone who made a homemade agility/obstacle course.
I know this is not for everyone, but I take the pups for indoor swimming twice per week. We do have a doggy pool here.
Underwater treadmill work is great too.
A few ideas for you. And congrats once again!