WS-ReliableMessaging is standard for ensuring delivery of requests to the destination service. soapUI supports it at both the request and TestCase level. For requests the WS-RM tab is as follows:

Enable WS-RM if desired (be sure your server supports it and has it enabled) and set the corresponding version. Now when sending the request soapUI will first initiate a WS-RM Sequence with the target service and use that for the request. After completed the WS-RM Sequence will be closed accordingly.
When running a functional TestCase containing many requests it is desirable to run all requests in the same WS-RM Sequence instead of creating new ones for each. Therefore the following tab is available in the TestCase Options dialog:

Enabling WS-RM here instead will generate a WS-RM Sequence for all requests in the TestCase instead of one for each.