Could you please try with that
Application app = new Application();
Package package = null;
package =
app.LoadPackage(@"DTSXPath.dtsx", null);
package.Connections["SourceConnectionExcel"].ConnectionString =
"provider=Microsoft.Jet.OLEDB.4.0;data source=" + Your file Name + ";Extended Properties=Excel 8.0; ";
Microsoft.SqlServer.Dts.Runtime.DTSExecResult results = package.Execute();
Your file Name-->Refer Your full file name
DTSXPath--> Path of your Package.dtsx i.e. (D:\SSIS\DEMO\DEMO\Package1.dtsx)