First take Simms' advice and check the warranty status.
If they won't replace it....
A temporary repair can be made with the hot melt cement mentioned by CD, (also called "ferrule cement"). It could last for years, but it's a bit brittle. Someday you'll make a cast and see the tip sliding down your line. On the "plus" side, it's easy to replace a worn tip guide without damaging the blank.
For a permanent repair, use a two-part epoxy cement. There are cements sold specifically for rod building, but any good quality cement is sufficient. If you fish enough to wear out guides, the tip will be more difficult to remove.
Depending on the rod taper, and the location of the break, your old tip might be too small. Replacement guide "tube sizes" are usually sized in "sixty-fourths" of an inch (incl half sizes). If the existing tip doesn't fit, take the rod to the shop to test fit, or measure very carefully.