Hi Boston,
i also stopped for 10 to 15 years from the age of 18 until 33 or so and now i'm playing again for about 5 years.
Don't worry about it it comes back very quickly.
What i do is start with a new piece and another one i already knew from my younger years but not a piece that bores me to death.
Play with fun and don't force anything because it is unlikely that it will go at the same pace. If you have this attitude, you will see that the learning pace can still be quite amazing!
Don't 'study' but enjoy = stop when it doesn't go well at that particular time.
Also very important: read about piano playing and technique from very good books (such as Sandor) which will make you a better self-learner. This is the best way to keep it up as it gives you no pressure whatsoever.
Topic: just started playing piano again after 20 years