Switching Templates

Hi,

I’m re-vamping my companies website. I’m not a fan of the template they are using and want to change it. However, when I do the information is all jumbled. Is there anyway, I can keep the website we have up and re-do everything on the new template without activating it? I essentially want to redo the website keep the same domain but keep what we have up.

I don’t want our site to look messy when it is up and am slowly overtime working on this site.

Thanks hope this makes sense.