soon we are going to change our server ip to another new ip and we would like to stay with the same rank is there any way to change the server ip to a new ip ?

The only way to transfer rank from one IP to another is to make use of the DNS feature. In order for it to work, both servers need to have the same ports.

If you've claimed the server, you can go to the Manage page and find an option to enter a DNS address that points to the server. Once you are going to get a new IP, change the IP the DNS points to to the new IP and wait for GT to update the page.

GT will re-check the DNS's IP once daily, or more frequently if the current server goes offline.