Remeron (your word Mirtazapine) is prescribed here in New York. most anti depressants like this do need periodical periodic medication checks due to other health conditions that the client may have, or because of possible severe side effects like kidney and liver damage. or because the medication the client may presently be on can interact or is a controlled substance. Remeron is not technically a controlled substance but like with any antidepressants standard medication check up with out having a local PCP (primary care physician) is monthly or every other month.
my suggestion is if you have moved and are now living here in New York is to have your our of state doctor recommend a primary care physician that you can now see. Primary care physicians here in New York are fully qualified to prescribe all medications that ones insurance company covers and all others too should you decide to pay for the remeron out of your own pocket if your insurance plan no longer covers it.