There are some achievements that I know I should have received, but are not completed. For example, I have before made a Glade potion at Peka Glade, but don't have that achievement, or the Token Shop purchasing achievements.

It's been a while, however, since I've done these -- am I just going to have to do them over again, or can I get my achievements still?

Most achievements are not retroactive, meaning that you will have to do them over again in order to get the achievement.

However, some require you to visit a certain page in order for them to activate. Your perf's and your pet's pages are often missed by people.

Poop. That's what I feared. Oh well....thanks for answering. :)