Add a 302 (permanent) redirect to make the most out of the old link. This way, the link will actually
help your web app because it'll sort of transfer the weight (search engine wise) to the new link.
I don't know what your setup is, but you can search for "302 redirect [SETUP]". There's a chance you're on Apache, look into `.htaccess`. If you'd rather not tinker with that, your hosting provider will most likely have a graphical user interface to add redirects.
All the best,