Have you exhausted all topics with Isabelle? She should still be giving you advice, if you aren't at 100% (I think).
And I know what you mean. The second time I had to get my approval rating, it seemed to take forever. It's only fun and new once.
Just keep talking to Isabelle, she will give you advice and tell you what you need to do. Talking to your villagers, watering flowers helps alot too. It took me almost two hours to get my approval rating to 100%. You will get there eventually
1. Design a town flag & town tune.
2. Place an item for sale @ Re-tail.
3. Pick up all trash & remove all weeds.
4. Run a few errands for your residents.