I'd restructure.
Have NeopetsJr be basically Neopets as it is now with some tweaks.
Add some learning elements to it.
Gives the younger players a hopefully fun and informative experience.
Earn NP through different educational games, possibly quizzes, etc.
Perhaps allow some tweaks from parents or educators to personalize the player's experience and make it a feasible tool for learning.
Then Neopets X (3.0?) would be geared for the teenage through adult audience.
Bring in some nostalgia.
More plots, battledome stuff, etc.
Re-release some old, lost, and forgotten items.
Possibly dedicate a server or few to the "Old Neo" experience where the look and feel of Neopets circa 1999 with periodical "updates" bringing it to current - have the ability to link accounts and earn bonuses, perks, etc. for your progression in Old Neo. Maybe offer like shared training for new pets created in Old Neo - any stats earned on either site are instantly reflected on the other; cannot be used retroactively.
Have a couple customer service team not only mod the forums but interact with players again at least 16-24 hours a day, 5 days a week. A way to bridge the gap between the players and behind the scenes.
Modernize the site, forums, games.
Expand to Steam with site bonuses; unique, one-time-use prize codes... then move to digital releases on consoles.
Bring back the plushies & key quest codes. Possibly other merchandise.
Revise the CCG - possibly do something along the lines of MTG/MTGO and Pokemon/Online directly connected to the site instead of its own thing or just a source of bonus codes.