Yes, e-maktab has now made it much easier for teachers/admin to update a classroom's attendance if they have missed out a student or even missed out the whole day's attendance register.
The process is the same. When you are taking an attendance register for a classroom you'll see a drop-down option. This drop-down will give you the previous seven days of attendance register.
Click on the date which you need to update the register for and this load the attendance data for that date. You can update accordingly and click on the save button.
Clicking on Today will load today's attendance data.