Refresh a repeater field on a backend form

Hi,

I have a backend form with a repeater element. I have added a partial button to it that when clicked calls a function on the controller.

The function carries out various tasks that include adding another repeater item. I would like after everything has completed to refresh the repeater element with the new entries.

I have tried various combinations of this code - https://octobertricks.com/tricks/update-single-field-in-formcontroller-using-ajax - with no success.

I can see using a debugger that the $this->formRenderField('fieldToUpdate', ['useContainer'=>false]); is using the originally loaded model not the modified version. Even if it’s saved back to the database and refetched prior to $this->initForm($model);

Any pointers will be gratefully received.