Resitting AS economics on top of doing A2 isn't really bad especially for AQA. Firstly because unit 4 macro is literally unit 2 in much more depth so everything you did at AS for unit 2 you're going to recap it so that is going to greatly help with your revision for unit 2.
For unit 1 micro though you're going to have to relearn it all again because unit 3 micro doesn't go over much of the stuff you learnt at AS, this will probably be the more difficult unit to revise for.
If you break down the marks at AS 25 marks for multiple choice, 5 marks for definition, 8 mark for comparing data, 12 mark for the analyse extract then the 25 mark essay.
The multiple choice will be a key component in getting an A/B so I would recommend doing all the past multiple choice papers, they repeat quite a few questions every year so if you have done all of them before and know the answers already to certain questions then you pretty much have free marks if they come up again. Multiple choice should be constantly done throughout the year to keep it fresh in your mind so you understand how to answer them correctly
The 5 mark definitions are just a case of you learning all the relevant ones and for the 8 mark it usually comprises of peaks troughs where they intersect or the whole time period of the data comparison (what it was at the beginning to end)
With the 25 mark essay I'm just assuming here but you probably need to brush up on your exam technique, so things like what is analysis and what is evaluation, you're going to need to work on these writing skills in order to achieve good marks. Again these exam techniques will also be improved upon in A2 as you're going to be answering more difficult essay questions so you're still doing revision for it but I would keep attempting past AS essay questions and get your teacher to mark them.
Like the multiple choice the essay questions tend to repeat as well in terms of what economic concepts you write for them and what your evaluation will be but you just tailor it for the wording of the question and what its asking for
The best way to revise is to keep attempting past papers for both unit 1 and unit 2, literally do every single past paper and do both of the data responses for every past paper, by the time it comes to your retakes you would have done all the past questions and be prepared for it fully.
The only problem I can see is you not having enough time to revise for it as you will be doing A2s as well, so I would suggest you plan out when you want to do revision for your AS, you do have till like may/june so you can do revision like once a week or something maybe switch between units every week you have a lot of time to revise so I would make the most out of it but consistency will be needed. Hope that helps