Hi lg,
Yes, you can use the info from your previous form but you will need to show that it is still relevant and that you have not adapted or learned to manage your problem/s. This is particularly important if you are trying to meet the Exceptional Circumstances criteria as the onus is 100% on the claimant to prove their case.
Whether or not your GP will write a letter of support probably depends more on Practice policy than anything else, you can only ask.
Even though this is not your first application, don't forget to make full use of our ESA guide and ensure that you understand the significance of any changes to descriptors since your last application.
ESA claims and appeals