Refresh LineMarkers

Hi, is possible to force a refresh for LineMarkers on the current file (or any file of choose)?

My problem is that I need to make some slow process (depending on a remote connection) to get the info for LineMarker, so I think the best solution is to start the http request when LineMarkersPass starts automatically (and return null) and then when I have the info from my HTTP request start the LineMarkersPass process again. Is this possible? or is there some better solution for slow line markers?