There is not much to "reset" on an IP address.
Wild guess - lack of information - is that you talk of the public IP address typically assigned dynamically by most ISPs. The related control on your router is here:
Home > Basic > Internet
The options available are:
Select an Internet IP Address radio button:
• Get Dynamically from ISP. Your ISP uses DHCP to assign your IP address. Your
ISP automatically assigns these addresses.
• Use Static IP Address. Enter the IP address, IP subnet mask, and the gateway IP
address that your ISP assigned. The gateway is the ISP router to which your router
connects.
On most ISP networks, and for most usage, "Get Dynamically from ISP" is mandatory, just very few - effectively almost no - exceptions.
Well possible, your router will still receive the same IP address from the ISP following a reboot. More and more ISP gave up the random IP addresses (from the relevant IP subnet of course), and continue to hand out the same IP address to the same connection. This is done to avoid abuse, to relief from high load on the edge routers, ... If the problem is that your public IP is banned on a certain host, application or service, talk to the service provider or operator.
