The phrase "hast up" is uncommon and may not have many widely accepted synonyms. However, based on context and intended meaning, it could be replaced with phrases such as "accelerate", "hurry up", "move quickly", "speed up", "rush", or "make haste". These phrases convey a sense of urgency and importance, indicating that one needs to act fast and complete a task or reach a destination quickly. Using different synonyms can add variation to the language and create interest in written or spoken communication, promoting better understanding and engagement with the person or audience.