Yea a simple “change departure date” can handle it so long as you are tracking context. Voice/ASR also streamlines that when that is part of the UX.
Also if you want to a very quick go back to just the previous Q/A, you can say “go back”.
Need to be careful with assuming webviews are the answer when dialog can sometimes still be an option. But I can imagine the case of a long and complex form where webviews can make sense.