Questions:

1. Is there a way to how to make my dog get more than 120 points?
2. Are Points Limited?

Yes, points are limited if creative is inaccessible.
For now, you may either use the Creative Collar or directly modify the NBT data.

How To Get More Points in survival???

You can get more point via the training treats, but you cannot pass the max dire level limit, provided that you are on survival with no access to commands .....

Oh I see, the treat you are using is the Normal Treat, you can only use it for a limited amount of time and the treat gonna become useless with the dog, you have to upgrade to the Super Treat by combining 5 Normal Treat with a Golden Apple without respect to the layout in the Crafting Table, there is several different tier and as you keep upgrading, the old tier will be "outdated" for the dog and you will have to use the higher tier.

So It means The Points are Limited???

My Dog is Only Taking 20 training treat, after it is showing in chat that your dog level is too high to gain anything from this treat

When The Dog reaches Ultimate level then it is not possible to give more points to the dog? Yes or no?:

Yup, it isn't, so choose wisely.

Oh, Okay, That was my question.

Hey, thanks for taking the time to create this issue and I'm sorry I didn't get round to resolving it. I've not worked on this project for a while and have decided to archive the git repository. Fear not, there is a fork https://github.com/DashieDev/DoggyTalentsNext which might be of interest. I don't expect to be back within the Minecraft community so farewell and happy mining!