Cisco Switch -- multiple networks on one switch ?

My current Windows DHCP server is running out of IPs,
therefore I was planning to change the SubnetMask from
255.255.255.0 to 255.255.252.0 on 100+ static servers,
routers, VPN tunnels, etc but do NOT have time to
right now, therefore I was just going to assign
a few statics in a new 25.x range.

I assume the below DESIRED is doable
without changing anything on my network ?

If not, what is doable ?

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CURRENT
  ** one DHCP server, 192.168.24.x
  ** one gateway, 192.168.24.x
  ** one subnetMask, 255.255.255.0
  ** one Cisco switch, 192.168.24.x
  ** multiple static clients, 192.168.24.x
  ** multiple DHCP clients, 192.168.24.x

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DESIRED
  ** same as above, but multiple static clients
     also getting assigned 192.168.25.x IPs