How do I reply to cancelled plans?

The wording tells you a lot. Someone who says she is wiped out and wants a new night is telling you she still wants to see you, just not tonight. Someone who gives a vague reason with no new time, or who says something like maybe another time, is more likely cooling off or juggling other plans. Those two situations call for different replies. If she offers a new time herself, your job is to say yes or name a slightly different one, and keep it simple. If she gives no reschedule, you have less to work with and the reply should open a door without pushing through it. Notice whether her message is warm, neutral, or flat. A warm cancellation usually needs a warm reply back. A flat one often needs a shorter, lighter reply, because she may be checking how much effort you put in.

There are roughly two kinds of reply that work here. The first accepts the cancellation and proposes a specific option, such as a named day or a clear choice between two. Its job is to take the planning off her plate. A draft is this kind when it contains a concrete alternative and nothing else demanding. It should leave out any mention of how she always cancels, any long explanation of what you had planned, and any apology for something you did not do. The second kind accepts the cancellation and lets her choose the timing, with a warm line that you would like to see her soon. Its job is to show interest without pinning her down, which suits a cancellation that came with no reschedule. A draft is this kind when it reads as relaxed and asks nothing specific. It should leave out any heavy phrasing about missing her, because at this stage that can land as pressure.

Cancellations often come late in the day, and the reply is best sent the same day or the next morning, not at 2am when you are still annoyed. A calm reply sent when you have had time to cool off reads far better than a quick one sent while you are irritated. If she has offered a new time, confirm it the same day so it does not drift. If she has given no new time and you have replied with an open door, give it a few days before you follow up, and make the follow-up a fresh, specific invite rather than a question about whether she still wants to meet. If a week goes by with no reply to a concrete offer, treat that as a clear answer. Send one more light message at most, then leave it. Repeated chasing after a cancellation is one of the fastest ways to end a match that was going fine.