What about working up slowly back to it? Maybe have wash with bucket water first? Set it in the bath so she can splash with the water from the bucket and you can sort of wash her down with it. I know its not the same as an actual bath or shower.
Then if she accepts that maybe have tiny bit water in the bath and increase it bit by bit?
Will she sit in the bath with her nappy on? You could try that then take her nappy off after she gets out and then clean her bits with a washer.