The human body does replace itself every 7 to 10 years.
Although it's not in the way that some people may think.
For example you're not actually getting a new body every 7 years or so but instead your cells in your body are reproducing and replacing themselves and rebuilding themselves every 7 years or so.
You'll usually notice significant changes in your bodies appearance such as in your face as your face change every 7 to 10 years.
So you may look different 7 years from now.
Your face changes much more quickly from the time you're born and until you turn 18 and then the body changes at a slower rate.
When you're an infant and then reach 1 year old to 2 years old you'll notice a huge change in your faces appearance as well as you've grown a lot in those years.
Your body and face are constantly changing over the years without you even realizing it.
Your bodies cells do reproduce at a nonstop rate, but you're not a new person every 7 years especially after you turn 18.
You still have the same body but your facial features can change and your body can still grow out wider.