Sorry to inform you that It will be a great problem for you. During the entrance in the examination centre , they will match the DOB with the Admit Card and the original photo ID proof you will take there. And due to the mismatch there is a great probability that they will not allow you to write the exam. Also if you have given the exam then also during the counselling there will be a great possibility of problems due to this DOB error.

Now what you can do is -
1) Search details about the UPSEE for which you are appearing and try to find out if they release a date for rectification of the details.
2) If they dont release a rectification date then you should contact the concerned authority via formal email or a call in the phone number provided in the website and get your problem discussed. They will surely let you know if there is a exception of rectification or not or any other way out.

These are two possible ways you can do.

I wish you Good luck so that your problem get resolved soon!!