In the game, your pet lives for 15 hours. You can extend
this time limit by going into a camp that you make, then the Pokegatchi
Pen. Afterwards, select "Set Pet Free". Your pet will
appear on screen. Re-capture it, but you must clean it up as it
will be just as dirty, hungry, etc. as when you first caught it.
The time will then go back to 0:00 for the age.