Well, the good news is its not actually dead. I suspect what's happened is you got it and put it straight outside - April was cold, and if the plant had been kept under cover or inside (most likely) the shock has caused the leaves to die back like this because it hadn't been hardened off.
This plant is not fully hardy and will be killed in a harsh winter - where you live, that's likely to be every year, so remove to frost free place for winter. In the meantime, cut back the leaves, removing the dead parts, and leave what you can that's still green. Keep out of cold winds for the time being, give it as much sun as possible, or at least a very sunny, sheltered spot. I don't know what you repotted in, nor how big the original pot was, but these plants like to be just slightly rootbound, and the best potting compost to use for them is John Innes No. 2 or 3.

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