If only the domain is changing, and the paths within the domains remain the same, use Ralph's suggestion. A search and replace like this:
replace "http://old-domain.com" with "http://new-domain.com" will do the job.
If you want all mentions of the old domain changed, leave off the "http://".
A good editor will hi-lite the found instances, let you inspect to be sure nothing went wrong, let you test a single instance, and then if all is copacetic, do a global replace (or some other action).