Doubt

You don’t if you’re retaking the December exam in the same year – they are based on the same syllabus. If it’s a new year, the syllabus would have changed slightly, so to remain 100% in sync with the new syllabus you should get new material. Having said that, lots of candidates do manage with older versions of the material, so it’s a choice you’ll have to make between what you’d prefer and what you’d like to pay for.

Good luck!