I would think that there must be some way to pull it out, try to get something that is small enough to go down through the tube with a lip on the end and attatch it to a slide hammer to try and pull it up and out. If you're worried about crud falling into the pan you could just run an air hose to the breather tube or into the oil fill to create a positive pressure in the pan to blow anything up and out of the hole. If you don't have a compressor you could just hook the exhaust tube from a shop vac to your oil fill, it doesn't take much positive pressure, if doing it this way you might want to plug the breather tube wit a rag.
If you can't pull it out you could try drilling it out with the positive pressure and some grease on the bit, I would be leary of this as you couldnt tell for sure if anything did fall in, if doing it this way I would drain your oil after drilling and then flush from th dipstick tube with the drainplug out to wash out any thing the grease and air didn't take care of.
If you don't want to drill it(don't think I would) if there is any nub sticking up I would find a tube with an inside diameter that will just slide over the nub and use it as a sleeve to put the tube back together using Ultra (blue,black or orange) Silicone.
If no nub try getting a piece of really thin wall tubing that will go inside and try splicing it together from the inside you would want to solder or braze the smaller tubing into the upper piece of dipstick tube so it can't fall in the pan and then use some silicone when inserting it into the short piece in the block.
Hope this helps,
Caleb
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