Sforno on Exodus 27:20/ספורנו על שמות כ״ז:כ׳

1ואתה תצוה, If, prior to this admonition, the Torah introduced its instructions with the words ועשית, “you will do, etc.,” the meaning had been that Moses was not to do this personally, but that he was to delegate the tasks in question. The formulation ואתה, however, means: “and you personally.” He, personally, was to issue instructions to the Israelites concerning providing the oil for the Menorah. He, personally, was to assemble Aaron and his sons and to address all the חכמי לב, “wise-hearted people.” (28,1 and 28,3)

2ויקחו אליך, as the need would arise in the future, after the Tabernacle had been completed. The people should not think that donating oil for the Menorah now was the only time that this commandment would be actual. It would have to be replaced from time to time as the supply kept would become depleted on an ongoing basis.