In every tama, there is a limit to any points you are able to recieve. ( Not just in Gotchi Points!!!)
So, you cannot recieve more points just for that reason. 9999 is the limit to the points you are able to recieve. Whyh they just didn't go to 10000, i do not know, but, if you want to gain points agajin, just go to the shop and my alot of items, or none at all -but you wont be able to earn points if you do not buy anything-. But, if your tama does NOT let you buy any items from the Shop, well I think your tama might have a glitch. Just get a pencil -sharpened with led- and stick it into the gray button on the back of the tama. It will go back to the most major event. If that doesn't work, then I am sorry.
I hope I helped!
- Citrus Fruit~*