Sure!
Open up a new Journal Entry and hit Correct. Follow the prompts and find or key the JE from last month selecting Back Out and Correct. When done, you'll have 2 JE's, the backout entry and the correction entry. Delete the backout JE. Now all that you have left is a correction JE that looks just like last month's entry, has today's date and will let you make changes.
Easy enough. Just don't forget to delete the backout entry!