how can I update the work which i have done, in the new model which is updated by my collogue.

That is a tough one.

Save your model under a new name to use as reference while recreating your updates.  You may be able to copy and paste your new features to the new model (you will need to be able select all of the references needed).

Which model has the most modification.  It may take less time for your colleague to update your model

Without understanding the structure of your models, it is difficult to suggest a best practice. @kdirth is suggesting that you evaluate which path is most efficient and there is a tool which may help you to determine this.

Compare part:

About Part Comparison (ptc.com)

I am almost certain the answer involves copy and paste.  If you don't know what I'm taking about, , please read up or see e.g., https://www.youtube.com/watch?v=5ipaDfK_qTo

Either copy and paste the features you made into the updated model your colleague provided.

Or copy and paste the new features your colleague added to the model your workspace.

(if you can group the features and copy and paste the whole group, this can make this task much more efficient)

Then both of you double-check the result 🙂