Miva Merchant readytheme navigation sets can be imported via a simple xml file. If you need to rearrange a ton of items do it in the file and import.

Importing is done via data management / XML Import.

The sample file:

<NavigationSet_Add>
	<Code><![CDATA[primary_navigation]]></Code>
	<Name><![CDATA[Primary Site Navigation Bar]]></Name>
	<Description><![CDATA[]]></Description>
	<Template>![CDATA[]]</Template>
	<Notes>#Set_Current_Time#</Notes>
	<Layout>Horizontal Drop-Down</Layout>
	<Items>
		<Item>
			<Active>true</Active>
			<Name><![CDATA[Shop All]]></Name>
			<Link type="Page" target="_self"><![CDATA[CTLG]]></Link>
		</Item>
		<Item>
			<Active>true</Active>
			<Name><![CDATA[Category 1]]></Name>
			<Link type="Category" target="_self"><![CDATA[category_01]]></Link>
			<SubItems>
				<Item>
					<Active>true</Active>
					<Name><![CDATA[Subcategory 1]]></Name>
					<Link type="Category" target="_self"><![CDATA[sub-cat-1]]></Link>
				</Item>
				<Item>
					<Active>true</Active>
					<Name><![CDATA[Subcategory 2]]></Name>
					<Link type="Category" target="_self"><![CDATA[sub-cat-2]]></Link>
				</Item>
			</SubItems>
		</Item>
		<Item>
			<Active>true</Active>
			<Name><![CDATA[Category 2]]></Name>
			<Link type="Category" target="_self"><![CDATA[category_02]]></Link>
			<SubItems>
				<Item>
					<Active>true</Active>
					<Name><![CDATA[Subcategory 3]]></Name>
					<Link type="Category" target="_self"><![CDATA[sub-cat-3]]></Link>
				</Item>
				<Item>
					<Active>true</Active>
					<Name><![CDATA[Subcategory 4]]></Name>
					<Link type="Category" target="_self"><![CDATA[Sub-cat-4]]></Link>
				</Item>
			</SubItems>
		</Item>
		<Item>
			<Active>true</Active>
			<Name><![CDATA[Category 3]]></Name>
			<Link type="Category" target="_self"><![CDATA[category_03]]></Link>
		</Item>
		<Item>
			<Active>true</Active>
			<Name><![CDATA[Category 4]]></Name>
			<Link type="Category" target="_self"><![CDATA[category_04]]></Link>
		</Item>
		<Item>
			<Active>true</Active>
			<Name><![CDATA[Sale]]></Name>
			<Link type="Category" target="_self"><![CDATA[sale]]></Link>
		</Item>
		<Item>
			<Active>true</Active>
			<Name><![CDATA[Featured Products]]></Name>
			<Link type="Category" target="_self"><![CDATA[featured]]></Link>
		</Item>
	</Items>
</NavigationSet_Add>

This was a snippet provided by Miva Nate from the page below. I don't know how long the page below will last (looks like one of those temp code sharing pages.)

https://snippets.cacher.io/snippet/0fdd0368b76e2e082cd9