Firstly I am wondering why you are only trying in July? They cycle year round...
One of your local farmers must have a bull you could take Delilah to? Even walk her to?
I bought Hillie in calf (she'd been running with a bull) and failed to get her in calf again - like you, AI three times.
I had fixed up with a neighbour that I could walk her over to the neighbour's Shorthorn bull if I needed to, then I realised
that each time I had AI'd her, there had been some upset to her routine.
Dairy cows are sensitive souls, they love routine and they get upset if things change. The first time she had come a-bulling had coincided with my weaning her set-on calf (because I needed the milk for my pet lambs.) Then the second time, with weaning her
own calf (because I needed more milk for the pet lambs!) Third time, with moving the 'milking parlour' as we were taking out the stalls where I had been milking her. Once I realised this, I decreed that I would not serve her again until I was certain I could go 6 weeks with NO CHANGES or upsets to her WHATSOEVER! It worked
Touch wood, no problems since with her or any of the other Jerseys - but I do make sure that nothing upsets them around the service and for several weeks after.
If none of that helps, you could get the vet to check that there's nothing wrong with Deliliah. Our vets reckon they can often help if a cow is proving difficult to get in calf - could be worth a try, rather than putting her in the freezer.