Hi Mad Mum
Try drawing up a practice timetable with your daughter, taking into account the likely amount of homework and the need to prepare for the 11+. Give her a couple of days off each week with no work at all, and plenty of small rewards for sticking to the timetable each day/week.
Far better that she does a modest but regular amount of work each week than she throws in the towel completely, and you and she become stressed.
I agree with Sally-Anne. I drew up a timetable for my son for the last three months before the test, I put on it all his other commitments so nothing would clash and then spread the work out evenly with a break during mid-week and at weekends (with an occasional practice test on a Saturday). I actually found he would come home from school, check his timetable and get on with it. I gave him a small reward at the end of each week.
I think having the amount of work set out in advance so your child knows what they will be up against helps to focus the mind, rather than coming home from school and not knowing for certain how much extra 'homework' they're going to have to do.
Best of luck.