Hi Christine,
"When I clone an object (Contract) which has a value of 1 june 2024, I want to change the value back to the original default value of 1 january 2030 (in the new cloned object)"
As I understand it, you have an attribute with default value January 1, 2030 and you want the new object to also have the default value and not the value of the previous one.
For sure a lot of Solutions. Mine would be to :
Create a Constant with the Default Value. When cloning the Object, change the $NewContract/Eindatum with the Constant.
Hope this Helps,