New design, how not to lose ranking?

Question

Search Engine Optimization

There is an old site, TIC 20. I wanted to make a new design, began to make up a new site and fill it with the same articles on the subdomain of the main one, and positions in Yandex immediately fell sharply.
Question: layout will take about a month, on which temporary domain should it be done so as not to lose the position of the main site in Yandex?
I will be very grateful for the answer!

Answer 1

There is an old site, TIC 20

Did you mean X?
That is, did you make a new site on a subdomain of the old one?
If so, then it was necessary to close the subdomain in robots.txt from indexing and add rel="noindex" meta tags on all pages. And make yourself calm.
But the drop in positions may not be because of this. Usually in such cases, the search engines stick together and that's it. The reason may be different.

Answer 2

On any domain, just set the login password