Welcome to RR.
First off are you trying to change your network IP, or the routers IP. You can not change the IP address given to the router by your ISP.
You should be able to change your network IP's within the given range as you stated. For example 192.168.0.1xx (Note:This is for a D-Link router) meaning the last set of numbers can be within the range of 100-199. I am not familiar with Netgear routers, Sorry. I would suggest that you try our sister site
TechIMO (Tech In MY Opinion). You'd get more help over there then here at RR.