I've completed all levels but Achievements say I have not
I've tried just replaying the final battles again but I'm not getting credit for the achievement. Is there anything I can do?
I've had this happen to me several times. Occasionally replaying the boss level triggered it, but other times the only way I've been able to resolve it is by playing each level in the world again in order. Since you already have that world's plants unlocked, the second playthrough is much easier than the first.