Router – How Can a Router Change the IP Address

What you like to perform is Policy Based Routing. By default, the L3 device define the next-hop based on destination IP. On cisco router, PBR allow you to route packet based on policy through Route-map. So you can create a Route-map and match traffic with an ACL and set a next-hop, after you have to apply in which interface the policy should be active.

Unfortunately on Packet Tracer, this features is not available so you can't implement that on you scenario.

If you have the opportunity to implement your scenario in a real equipment lab, here are the commands to configure PBR following your topology.

route-map ISP-Outside permit 10
match ip address INTERNET-ACCESS_192
set ip next-hop 192.168.2.1 
route-map ISP-Outside permit 20
match ip address INTERNET-ACCESS_172
set ip next-hop 172.17.138.1

interface GigabitEthernet0/1 ! in all interface you want to implement this policy 
ip policy route-map ISP-Outside

ip access-list extended INTERNET-ACCESS_192
permit ip 192.168.2.0 0.0.0.255 any
deny ip any any

ip access-list extended INTERNET-ACCESS_172
permit ip 172.17.0.0 0.0.255.255 any
deny ip any any

Also see Policy-Based Routing on Cisco's documentation site.

Your drawing and idea have some problems:

• Your router has multiple interfaces in the same network, but that will not work. Routers route between networks, not from a network back to the same network, so router interfaces must be in the different networks.
• Switches are layer-2 devices, and they are ignorant of layer-3, e.g. IP. Layer-2 can carry any number of layer-3 protocols (IPv4, IPX, IPv6, AppleTalk, etc.) because they do not know or care about layer-3.

The idea of changing IP addresses on packets is NAT (Network Address Translation).

A real problem for you is that on whatever network a PC connected, changing the address on the PC to a different network address will stop the PC from communicating after you change the address.