Well, it can go 2 ways.
1-Either Take the active people and make a new academy
Or
2-keep this one.
1- + Its more attractive to start a new academy since the older posts here and lack of activity makes it seem 'dead' or 'un-active'. So making a new one with active people is a good way to go since everyone sees a new 'active' community.
- You have to start over again. may never see them again unless you mail them with the new academy name 'if' they were to go active again.
2- +Not bad to keep the old one. Older posts that remind you. people that come back after a while go active again. usefull posts, all the hard work put into this will be kept and not going trough the pain of setting everything up again
- personally it doesnt seem attractive. old outdated posts may scare people away because its 'un-active' so wich means its harder to get members
Anyways those are pros and cons for either option, both have good and bad sides altho in the end its a desicion you can only make, im sure active members will support you and even new members like me will.