Hi qwerty900 welcome to the communities,
Please give us more info about your environment because I don't really get what you are worried about here: "attach it to the current cluster without losing the hosts on the datastores?"
You don't attach a vCenter to a cluster.
You install a new vCenter and add the ESXi hosts to the vCenter. The cluster, which was just a configuration in the database of the old vCenter will be gone, but your VMs and datastores are connected to the ESXi hosts and will still be there.
Regards