It is much easier to update your resume periodically than all at once, so even when you’re employed, set a reminder to refresh your resume every three months, while the information is still fresh in your head. This will make your next job search much easier, should you decide to switch companies or careers in the future.
In the short term, you should tweak your resume based on each job you apply to. For example, if one position you’re applying to seems to weigh a certain responsibility or focus over another, you should be sure your resume conveys your expertise in this area. At the same time, you should be updating your resume with your experience as it develops, adding any new skills you’ve learned, courses you’ve taken or awards you won.