Simply change or add the new URLs to the paths
section in your .hg/hgrc
file. You can define different paths to groups or servers, for example:
#hgrc
[paths]
default = /somewhere/in/the/local/repository
group01 = https://example.com//absolute/path/in/remote/server/repository
...
As manual explains there are the special default
and default-push
paths.