Children taken ....Law question

In CPS case when is the case closed? After the children are adopted? How easy or hard is it to go back to court and get kids back home with you after they are adopted or case closed? I ask because my children were taken away in divorce custody case not CPS. But CPS gets involved often. In divorce even after you sign divorce order you can always always file motions and go back to court and change the custody, parenting time orders. For 18 years you can keep going back to court and changing the custody. ( I can request or ask to change custody, that does not mean they will, sometimes the judge will punish me for asking for more time with my kids and take away all my visitation for 12 months, this happened twice, but I can always file a motion and go back to court and ask for more time with my kids ) So I don't understand exactly how it works in CPS cases.