Here is how I would do it.
Assuming this in your test case. There is a step which invoke a soap request and gets the response. Add a
Script Assertion and below is the script. And what this script does is that it will read the response, checks if it is not a soapfault and extract the required
xpath value as you desired and saves it at test case level property, say
VALUE_FROM_PREVIOUS_RESPONSE is property name.
//asserting if the response is soap fault
assert context.response.toLowerCase().contains('soapfault'), "Response is soap fault"
def holder = new XmlHolder(context.response)
//You need to replace the xpath in below statement
def sValue = holder.getNodeValue('/your/xpath')
//asserting if given xpath has any value
assert sValue, "Xpath does not have any value"
//saving the above value at test case level property VALUE_FROM_PREVIOUS_RESPONSE
In the next test step request, use the above property where ever you need above response value of previous step. That is known as property expansion.
Hope this helps.