Use Plus!'s autoupdate feature =)
XML code:
<ScriptInfo>
<Information>
<Name>Name</Name>
<Description>Description.</Description>
<AboutUrl>Website</AboutUrl>
<Version>Version</Version>
<UpdateId>6~8 character unique UpdateId</UpdateId> <BuildNumber>A buildnumber, natural number that grows one by one. (00, 01, 02...) </BuildNumber> </Information>
...
(Note: then your script has to be in Plus! script's database =) )