What is the best way to do this site redirection

Have a site in which we are pointing some links to "www.example1.com". Recently "www.example1.com" changed to "www.example2.com". Now if we access "www.example1.com" it will automatically redirect "www.example2.com". In "www.example.com" still it point to "www.example1.com". How its working now is... www.example.com ->www.example.com- > www.example1.com->www.example2.com. In our site all links are hard coded. Question ? What is the best way to do it. Continue to leave it like this or need to update all hardcoded values.(issue is in future if update this url again we need to update code again).

Please help me with some suggestions.