Hello,
If you donated for Donator Level 1 before the automated donation system, you will need to donate additional £5 to upgrade to Donator Level 2. You do not have to worry about your donation log.
Basically, if you donated for Donator Level 1 before the automated donation system, your donation amount is default to £5. The same goes for every other donator level (£10 for Donator Level 2; £20 for Donator Level 3; £30 for Donator Level 4). If someone donated for Donator Level 2 before the automated donation system, they will have to donate £10 for Donator Level 3.
Let me know if you have any questions.