Adding damage to a spell of a single damage type

Is there any way to add additional damage to only fire spells?  Ex. One of my players received a home-brewed magic item that grants her +1 damage on all fire spells. Is there any way to account for this automatically, possibly with global damage modifier, macro, or script? I know I could change the spells to have +1 damage but some spells such as chromatic orb are sometimes effected but wouldn't always be effected as they could have different damage types depending on the casters choice.  Any thoughts would be appreciated!

There is a script called Customizable Roll Listener, by Scott C, that could probably do what you are looking for. The script monitors the chat, and looks for text patterns occurring in designated roll templates. If you can figure out a matching pattern that will catch spells cast by her character that contain the word "fire", it could conceivably run a macro that calls up a "plus one hp" message. But realistically, if it were my table, I'd just ask the player to remember to mentally add a point  whenever they roll fire damage.