New website redesign question

Hi,

I currently have a website however, I've paid to get it redesigned from the ground up from a different company.

It's about to go live and my current website is ranking well.

Will the new website keep the same rankings or will it dip?

I've asked them to keep the exact URLs but some of the URLs on my current website won't be needed.

Before it goes live I need to make sure everything is done the best it can be in order to keep my current rankings.

Please can any SEO experts give me advice on what's best to do?

Thank you.