Move a whole day
Open the schedule. Tap the day you need to move. Pick 'Reschedule day'. Pick a new day. Keep Up checks feasibility (can we fit this into an already-busy Wednesday?) and tells you what conflicts.
Tell the customers
Tick 'Send rain note'. Keep Up drafts a kind, brief message in each customer's language ('We'll visit Wednesday instead because of the weather'). You approve. It goes.
Partial moves
Only some jobs can be moved? Pick the ones that can. The rest stay, reassigned to different workers or weather-hardy tasks.