Yes you can! If you go into the settings to adjust how the trip is built, the planner will automatically rebuild around that new drive time, unless you have chosen a blank trip to start with.
You can opt to keep all the new suggestions, or you can rebuild around the new drive times by opting to replace campgrounds. There is the option, when you rebuild, to lock any campground in the list you do not want to lose in the process. Very easy to keep your custom addresses without having to re-enter them!