Unfortunately, declaring a hiatus would not have helped. As we state in the rules and on the AC, missing two activity checks in a row for any reason is an instant drop; this is to keep someone from repeatedly avoiding the AC by declaring hiatus every month, or just by being on hiatus for an undisclosed period of time and never returning. The only way to avoid being dropped after two is to have mod approval for an extra-long hiatus that will span multiple ACs (e.g. 6+ weeks) or to respond to the AC while on hiatus.
You are completely welcome to copy-paste your old app during our September/October app period, which starts September 25. We will all look forward to having you back. ♥