Reformist (noun)

1. A person who advocates for or works towards making changes to a system, organization or society, often with the goal of improvement.
2. A person who supports political or social reform.

Origin:

From the prefix re- meaning again and form meaning to change the form of something, and the suffix -ist meaning one who practices or advocates a particular activity.

Examples:

1. He is a reformist, who has been working for the betterment of education system in the country.
2. She is a political reformist who advocates for changes in the electoral system.
3. The reformist movement has been pushing for changes in the criminal justice system.
4. Reformist ideas have been gaining popularity in the country.
5. He is a religious reformist who believes in modernizing the traditional beliefs.