All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
There is no sin on you if you enter Makkah without assuming the state of Ihram. You do not have to perform ‘Umrah every time you enter Makkah, especially since your need is repetitive, as you mentioned, so your obligation to enter with Ihram every time is an apparent hardship.
Abu Al-Walid Al-Baji, may Allaah have mercy upon him, said in Al-Muntaqa, about one who enters Makkah for a frequent need: “For those whose entry into Makkah is repeated, like the carpenters and the woodcutters, there is no harm on them in entering Makkah without being in a state of Ihram, and there is no difference of opinion over this issue because hardship befalls them by assuming the state of the Ihram repeatedly and performing all rituals…” [End of quote]
Allah knows best.