There might be options to backup the configuration, then reinstall the host on the SSDs followed by restoring the backed up configuration. This could become tricky if advanced features are in place, e.g. NSX-T, in which case you'd need to install additional vibs prior to restoring the configuration.
Taking into account that the partitions/sizes in ESXi 7.0 change, and will largely differ between an upgrade to v7.0, and a new v7.0 installation, you may consider to reinstall the hosts with v7.0.
André