Yes you can recreate. The easiest way to use the same invoice number is to open the client matter and on the invoices tab change it from Use Global Invoice numbers to Next Invoice number. Enter the number you want to use. Then run and approve your bill using appropriate filters and invoice date. 

When you are finished go back to the client matter and change it back to Use Global invoice numbers. 

Since you state that it used the same invoice number as the last month, almost assuredly the last month's bill was cleared after approval.  There is a setting under Setup, Bills to "Reuse invoice number..." that would cause that. 

That said, you should be able to undo, or clear from proof the current incorrect bill, then generate the bill with the same dates as the one that is missing, and the invoice number should be re-used once again.