Since you mention the electricity package, I assume you're in Ireland. So I'm basing this on that assumption.
If maintenance can't be agreed between the parents, it needs to go to court for the judge to decide. If there are additional needs that require therapies etc, evidence of that needs to be included in the court documents, and the judge may decide to increase the maintenance accordingly, or add to the order that other expenses should be split as far as I know.
I know someone who went through the Irish system and was told that as she couldn't provide any evidence that the appointments were necessary, and not just something that she wanted to do for her dc, then dad would not be splitting the cost. Although, she got herself into a bit of a pickle with schools - tried to claim the child had severe asd, as well as other additional needs, then got into a whole situation as she had described the child as so extreme that the child was supposed to go to special needs school, and mum had to quickly backpedal so the child would go to mainstream school, which was also outlined to the court.
Also, just so you're aware, and still assuming that your in Ireland, dca may be payable for children with asd, so it could be worth applying for that too.