Gov. Eliot Spitzer is considering scrapping a $1.8 billion expansion of New York City's convention center in favor of a bigger design.The governor will meet Monday with Sen. Charles Schumer, a critic who has called the current expansion plan too small, as well as Mayor Michael Bloomberg and Deputy Mayor Daniel Doctoroff, who hammered out the plan with the Pataki Administration.The expansion would add 1.1 million square feet of exhibit space to the Jacob K. Javits Convention Center, from the current 760,000 square feet. Meeting space and a hotel are also proposed.