Entity model context

Question

i have changed my model context.cs code like :

public productesEntities() : base(DBConnection.ConString)

{

}

 

replacing  "name=productesEntities" to DBConnection.ConString

that DBConnection.ConString read connection string from web.config 

 

problem is that at ecery time i update procedure or add table  DBConnection.ConString changed to old 
"name=productesEntities"


How can i keep "DBConnection.ConString" not "name=productesEntities"