Change it to be a console application run by the scheduler (no button - just do it) or set it up as a windows service.
You can use command line arguments or configuration files, etc. Give something a try and let us know if you have a specific problem
[EDIT] - Some articles you may find useful:
C#/.NET Command Line Arguments Parser[
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Powerful and simple command line parsing in C#[
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(There are several others - search for Command Line Parse in the search box at the top of this page)
Also:
Creating a Basic Windows Service in C#[
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Simple Windows Service Sample[
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Again - there are lots more articles here on Code Project on the subject