Were you suffering from any stressful situation that meant you were less 'with it' than normal which is why you submitted the draft instead of the final version?
Mitigating circumstances such as mental health, family problems, trauma, bereavement (etc) would qualify you for a resit without a cap where I work. However just saying ' 'I just made a mistake' would not.
If you can show that you were suffering from circumstances that affected your ability to properly complete your assignment and have some sort of proof of that, then you might be awarded an uncapped resit.
I just though it was worth making that clear because my friend just got the start time wrong for one exam (turned up in the afternoon instead of the morning). In our place he wouldn't have even got a capped resit as you need to get a minimum mark to qualify even for that . This meant she would not graduate until the next semester and would have to pay to take the whole unit again
When she told me what had happened she was just going to accept she had been ditzy (albeit she was really upset) I reminded her that her dad had died less than a year ago and she was still grieving.
Although she was doing relatively well on her course, she just hadn't made the connection between this bereavement and her being generally less 'on the ball' as a result.
She did make an application for her circumstances to be taken into account after the exam. She wrote a statement and provided a death certificate and they agreed and allowed her to resubmit work for uncapped marking
Read the regulations on applying for mitigating circumstances at your university before accepting a capped resit. They must have them. They should be on their web pages or ask for a copy from the office or from a tutor