レギュラー is the loan 'regular,' in sports context meaning 'a regular starting-lineup player.' 人一倍 is a fixed compound meaning 'twice as much as others, more than anyone else' (literally 'one-person + one times extra'). なくっちゃ is the ultra-casual contraction of なくては ('if not' → must), with the small っ for sharp emphasis. The whole line is a self-motivating declaration typical of sports-drama characters.