Need some help limiting a simple refresh macro to a single workbook

[wastewaterguy]

I am not super well versed in VBA but pretty good with excel. I need to run some simple code to keep a sheet refreshing every so often, but it would refresh all open sheets which I do not want. I attempted to restrict it to a single sheet which works great until i open a second excel sheet. can someone help me out with this?> I greatly appreciate!

Sub Autpen()
Workbooks("RefreshTest.xlsm").RefreshAll
Application.OnTime Now + TimeValue("00:00:01"), "OpenMe"
Workbooks("RefreshTest.xlsm").Close False
End Sub

Sub OpenMe()
Application.OnTime Now + TimeValue("00:00:30"), "Autpen"
End Sub