You’ll need to change the DNS of your Domain to point to your new Droplet.
Basically, at the moment the DNS of your Domain is still pointing to your previous Droplet. What you’ll need to do is first check where your NameServers are.
NameServers tell the whole world where the should look for your DNS. Basically, when I try to load your website, my computer sends a request and sees where your NameServers are pointing at and that’s where it’s searching for the proper DNS records. So, what you can do is use the website:
In there put your domain and from the DropDown menu next to the domain box select the NS line and click Search. This will show where your DNS is being managed.
If it’s DigitalOcean, you can change the DNS record from your Control Panel, if it’s somewhere else, you’ll need to contact the support there to help you sort it out.
Once you know where your DNS is being controlled and you can change the DNS. You’ll need to change two records your main/root A record and your www A record. Both there records will show your old droplet’s IP address. Change it to the new IP.
If your DNS is being managed by DigitalOcean, check the following documentation. It can show you how to manage it properly: