[AccessD] Best way to requery a list box in Access 2003

I have a data entry form that uses dropdown lists to verify data exists.  If the data does not exist, the user is redirected to the entry screen for the missing information.  My problem occurs when the user closes the second entry screen.  The list box on the first screen needs to be requeried, but I cannot seem to find the correct location to place the command.  Any suggestions???   
 
 
Jeff B