It sounds like your XEP has a static IP address in it. When you do a "find" in the ElkRP software, it is broadcasting UDP packets looking for XEP's. Since your new IP range is 192.168.1.x and the XEP is possibly still at a 192.168.2.x IP, the XEP will never see the UDP broadcasts.
You will want to look at the bottom of page 23 for the title "Forcing the DHCP/IP Address Settings to Known Values:". This paragraph will explain how to get the XEP back to DHCP. Once it is back at DHCP, you should be able to find it by doing a "find" in ElkRP.
A quick and easy:
Power off the XEP.
Place a jumper across JP2
Power up the XEP.
First, you will see 5 blinks of the green LED on the enclosure where the CAT5 plugs into.
About 30 seconds later, you should see a blink rate:
DHCP: 1 quick blink
STATIC: 2 quick blinks
If you see 1 quick blink, remove JP2 and the device will contiue to boot up in DHCP mode. After the device is running, do a "find" in ElkRP to see if you can find the XEP.
If you see 2 quick blinks, power down the XEP with the JP2 still shorted, and power back up the XEP. You will see the five blinks of the green led, and @ 30 seconds later, you should see the 1 quick blink rate. Remove JP2 and the XEP will continue to boot up in DHCP. After the device is running, do a "find" in ElkRP to see if you can find the XEP.
Hope this helps!
P.S. johnnynine's method will work as well and may be easier... Set your PC to a static IP address in the 192.168.2.x range and perform a find in ElkRP. If you find the XEP, connect up to it and set it to a static IP in the 192.168.1.x range.