All Main Cabin and higher awards look to be able to be re-deposited with no fees up to departure time (despite website mentioning a $150 redeposit fee for awards originating outside US/Canada). DL looks to be having some sort of sale on coach/C+ awards between LAX/SEA and HND for September only -- 25K BE/35K Main/40K C+ one-way before Amex 15% discount. No love for other DL gateways to/from HND in September (although they do look to have slightly discounted awards from normal award rates for September).

Note that the fare rules only require that travel commences in September. So if booking a roundtrip award, you can fly outbound in September and return in October or later and still qualify for these awards in both directions.