If you have other zwave devices in your house, you can try moving the Smart Switch to its final location, and issuing a zwave mesh repair command to your hub.
Here is some information about how to repair your mesh after you’ve moved the switch:
Here is some information about zwave signal strength:
The short answer is that adding more mains powered zwave devices to your system can help get signal to far away corners of your house. Battery powered devices do not act as repeaters.