Does Websites Re-Designing Or New Updates Affect SEO Ranking or Work?

If you are changing the design of a website it will not affect your SEO so long as you keep your URL structure the same. So if your URL i.e www.mysite.com/mycategory/my-page then you wants to make sure that you use the same URL when implementing the new site. It is the URLS and the page content that have gained Google trust and not the design itself.

If you are changing the sources code (backend) your site uses (.html to php) and just cannot keep the URL structure then you will need to make 301 redirect every single page to its matching page on the new site. (Eg www.mysite.com/mycategory/my-page.aspx will need to 301 redirect to www.mysite.com/mycategory/my-matching-page ). Unfortunately, when you change the URL structure there is always some loss of page authority even when you have a 301 redirect in place.