Create a new dhcp scope or extend the old one?

Hello

All help will be greatly appreciated.

We are going to change our subnet mask as follows: from 10.164.231.xx 255.255.255.0 to 10.164.230.xx 255.255.254.0. My question is about dhcp scope. Is it good idea to keep the old scope 10.164.231.51 to 10.164.231.200 and create another scope to add more ip addresses? or just delete the old one and add new scope with the range 10.164.230.10 to 10.164.230.254. Thanks again for your help on this issue.