Question

I will spend personal time if necessary to make up for mistakes i have made.

Answer 1

Agree! If you have made mistakes, it often takes personal time to make up for the mistakes if necessary.

Answer 2

if this question is asked in a job interview, you should answer with 'I agree'

This answer convey that you're a very responsible person that will always stand for your principle and ethic.
The company will see you as an asset that will benefit the company.