If you use the control template and configure on the entry box to refresh after lookup that should work though.You can also configure for other fields to be updated. It may be worth checking that you have configured up both the button and related entry control correctly.
As the reset method only updates registered items, you will have to provide code to update other elements. For non-template lookups I sometimes add the DISPLAY(?A,?Z) line in the ThisWindow.Reset embed point so they get refreshed when the ABC items do, if an ABC refresh for registered items like a browse list is going to happen anyway. It is a good place for any secondary lookup or colour/font changes on value etc. too. If you don’t have any registered items you could still use that embed and call it.
I hope this helps, regards Jim