When a reaper is on the verge of death, she will recall the beauty of life and her desire to protect it. It's similar to when humans recall their lives. She will think, "I've done my job", then start to feel euphoric, peaceful, and accepting of the fact she's dying. 

The thing is, not many reaper know that this happens. The ones who would, would be doctors, self-proclaimed scientists, and reapers themselves who have almost died. 

The fact that Wescott recalled these things meant she was dying. Luckily enough for her that help came their way. 

Had she meant to tell Luka she loved her? In my opinion, yes. She could've kept these thoughts inside, but she wanted to tell them to Luka. She wanted her to live. 

(I think though, it shouldn't be confused that this is the same kind of love felt by humans, but the reapers' own way in a way; a love (or something close to it) that is felt for everything such as life itself, not individually).

(That doesn't mean reapers can't have preferred humans, though. As known.)