Rita's fingers haven't stopped moving all this time, but they do shortly after Strange asks his question.

"Plan to?" Rita faces him with a smug grin. "I've already done it. Take a look for yourself."

The easiest way to dramatically change a spell like this is, of course, to change the point of exit. One who passes through the ice will find themselves not in a cabin, but atop a frozen lake, surrounded by snowy mountains. It's where Rita went skating with Yuya the other day, and it's the first place to come to mind when she had to think of a location with a similarly smooth, mirror-like surface.