J.L.
I know people will disagree with me....but I am still going to throw it out there.
Let her cry it out for a few minutes. At 15 months she is plenty old enough to learn that VERY important skill of self soothing. Let her cry, go in after as many minutes as you can handle, cover her up with her blankie again and give her a pat on the back, say it's time for sleep and leave her be.