Increasing your credit limit requires you to have a good standing account with the credit card company and you must have the credit card account in good standing for a year or more.
If you've got a good payment history with your credit card company and you've had the credit card account for a year or more then you will need to call the credit card company and ask for a credit limit increase.
There's no guarantee you'll get a credit limit increase but you can try to get a credit limit increase by calling the credit card company.