I have this domain 5 years old and it had a hard to use design for the visitors. I decided to redesign it. The site presents some event planning services, which is kind of a family bussiness. ( but no importance :) ) I changed the website design and also changed it from .html to .php files , also added some new pages. I used a .htaccess redirect from the old pages to the new ones. ( for example sound-services.html became services.php?name=sound ). The content is pretty much the same, and google indexed just fine de new pages. BUT
The site was in top 5 search results on a lot of keywords and week by week the website was falling in position. Now i found myself on 50+ results return even at 300+.