Manager not willing to negotiate notice period

I have put down papers a week back and wanted to get relieved by 2 months - my company has a notice period of 3 months PFB the text under notice period section in my appointment letter: "In the event of your resigning from the services of the company, you will be liable to serve "notice period" of 3 months (90 days) or pay a sum equivalent to the basic salary for the number of days un served, which will be calculated from the date of resignation letter to the date of relieving. Relieving letter will not be issued unless amount, based on the above is settled by you, along with any other dues payable to the company." Concerns: 1) My manager is not willing to negotiate notice period of 3 months even though my KT plan is only for 1 month and I don't have any other dependencies 2) I was able to negotiate a joining date with my new employer only to a maximum of 2 months (they initially wanted me to join in 2-3 weeks) Additional Details: 1) I have a balance of 50 earned/privilege leaves Please guide me on the options I have to get relieved in 2 months. Greatly appreciate your help