The exact thing happened to me when studying for my Gcse, i must admit i never till the day before my exam go the motivation i had over the break back, this definitely affected my maths mark.. anyways what i would advise, is whats helping my get through my A levels, not wanting to feel the same feeling that i did when i completed my Gcse exams feeling like i didn't do enough, there's nothing better than walking out of an exam knowing you did everything you could to get that A*. For English Literature i used a lot of blogs which i then created my own point of view for with regards to analysing work. For the rest of my subjects i did a lot of past papers. I know it may seem impossible to find the motivation but with 6-9 hours of revision, this tell me how dedicated you are to your studies so DO NOT give up now! Wishing you the best of luck for your upcoming exams!