Hi linda
Leaving food out will not encourage the hedgehog not to hibernate. I usually keep leaving food out for about a week or so after I have seen the last hedgehog. Depending on the weather and other factors, some hedgehogs, especially some females who have had later hoglets as well as some hoglets themselves, don’t disappear to hibernate until into December. There are no hard and fast rules. Occasionally a hedgehog will decide not to hibernate, but it is the exception rather than the rule and does not seem to be dependent on whether or not you are still feeding. I had one here last year, but his Mother and sibling disappeared to hibernate, despite the food still being available.
I would be inclined to cut the water melon out from your feeding regime. It must be expensive and does not add anything nutritionally to what the cat food provides.
Good luck with the hedgehog. I hope it has a successful hibernation, when the time comes, and returns again next year.