Yes! It's pretty easy to do...so long as your bankruptcy case is still open.
You can amend your bankruptcy papers to include any debts that you forgot to include when you originally filed. However, you must have incurred that debt prior to the date you filed bankruptcy. You cannot add any new debts that were incurred after your filing date. Also, there is generally a filing cost associated with amending your bankruptcy papers. Here in the Central District of California, that cost is $30.00.
If you have received your bankruptcy discharge and your case has been closed, it is still possible to amend your bankruptcy petition. However, you must reopen your case in oder to do that. This is a costly and time consuming process. Because of this, it is important to list all your debts with the original bankruptcy petition and make any needed amendments before your case is closed.