I am trying to the update the JSP name on one of the Business transaction filter which has 1 year worth of data. If I update the BT, would it wipe the historical data or would it append the new value going forward and keep historical data intact?
If you update the filter it will just start evaluating a different way. The historical data will remain intact and from the point you change the filter the new data will generate as it should. One thing to note here is that if you have one of the "aggregate" splitting options selected for a custom splitting then your new transactions will probably go into "<...>" as a splitting entry. Does that make sense? If you want to reset the splitting go into the BT's splitting options, and at the bottom choose your Application and hit 'reset'
Hope that helps,