I would suggest trying the split cage method and try to get them to get along again.
If you are unfamiliar with the split cage method, here is how it goes:
The split cage method is when two small animals are not getting along or you are trying to introduce them. Though you do not have two cages, this is a temporary setting until they get along. You split the cage with mesh wire, a lid, etc. where they can still see and smell each other. Every day, switch the mice, so if one is on the left, switch her to the right and if the other one is on the right, switch her to the left, so there will be the smells of the other mouse. After about 1-2 weeks, or whenever you feel they are ready, take out the divider
For more info on the split cage method; (I can't add a link but, Google split cage method)There are many great websites out there that can help for sure! I hope this helps
Ming (pug) 13 years
Mei-Mei (pug) 4 years
Teagan (Gerbil) 2 months old