@Sooi **************
, you can't ever renew a visa (or an extension) inside or outside the country you get a new one every year
If you have stamps like this in your passport you are on an extension of stay.
AND
if you want to know the correct way to do it you should go cancel them at the immigration office by showing them the date you're leaving and they will give you a new stamp good until that date only
This is what an extension stamp looks like. (this one is for retirement) yours would be for taking care of your child here.
As long as you don't intend to come back here you could leave and they will run out BUT if you ever come back and want to get them again you will have a problem if you don't cancel these