Hello kingsisle. When i run out of pet energy, and dont have enough crowns to buy a refill I GET STUCK! Can you possibly consider a shorter refill time say, 5 minutes?
The refill rate is currently 144 points/day. This means with careful planning, you could run an adult 24 times. If you earn 4 points per run, and feed a 4 pt snack, you would earn 192 points, or just under 3 days to earn those 500 points. In a week, from start, you should be working on Epic level.
Now, you can even boost this, without crowns, but leveling. A moderately played character should epic his/her pet out in under two weeks with a dedicated effort.