If your website was built over twelve months ago then it may be worth having some of the code updated. There are new techniques coming out every day when it comes to coding and often these new techniques are more secure as well as improve page loading times etc.
If you use a content management system such as WordPress you can quite easily update it through the admin panel, but be sure to take a full back of the site prior to doing this. Even if you update the content management system, you may still need to update other parts of the code that are not changed during the WordPress. Some code and site updates may cause other issues within your website, for this reason you should be sure to thoroughly check your site once you have completed any updates to make sure that everything is functioning as it should.