your father need a psychologist who can work with him on motivational interviewing its a technique where in you make the client feel motivated to work on his problems.
Next Steps
See a psychologist for your father who can help him motivate to work on this issue.
Health Tips
Be a support as alcoholism has deep roots and parental Schemas and need very high level of family support during and after the therapy or de-addiction treatment. Also ensure he goes to follow up meetings and support groups after his treatment is done.