Rebatching is a soap making method where you take existing soap shreds, melt them down and pour into molds.  Rebatching also allows you to add essential oils, fragrances, butters and botanicals that would have been altered if added during the Cold Process soap making method.  Rebatching is a good way to get the feel for soap-making without having to handle any caustic ingredients.  You can also use a double boiler, crock pot or oven to melt your soap. Takes about 2 hrs. to make.

Crock Pot Method:

Start by measuring out 4-6 cups of shredded base soap or as much as will fit into your crock pot without going past the half-way mark.  Measure out about 1 cup of milk (you'll add this as needed, you may not use it all or you may need to add a bit more).  Add ½ cup of milk to the crock pot and the shredded soap, put the lid on the pot and set it on the lowest temperature setting.  Check the mixture every 15 min. or so and gently stir with your wooden spoon, but try not to make bubbles.  If it looks very dry, add a little more milk, and so on, until all the shredded soap is melted. 
After an hour or so, it should have the consistency of soft mashed potatoes.  It also may look lumpy.  Add about ½ cup of powdered milk (not reconstituted).  The powdered milk will make the mixture very smooth and easy to pour.  Go ahead and add any additional ingredients, such as Vitamin E.  You can also add additional oils ( ½ -1 tsp.) such as castor (for shampoo like lather), almond oil, apricot kernel oil or jojoba oil at this time.

When you're ready to add your colorant, herbs and fragrance, remove the amount of soap needed for your size mold from the crock pot and place it into the measuring cup.  Mix in your final ingredients (amounts of color, herbs, fragrance will vary depending on your liking) and pour into molds.
The soap should be easy to pour, but not too runny.  After pouring into the molds, tap gently on the counter to remove any air pockets and smooth out your soap.  Leave your soap in their molds overnight, or until almost dry.  If you're having difficulty removing from the mold, place mold into the freezer for several hours for easier release.

Cure them for 1 to 2 weeks on a drying rack.  Wrap individual soaps to preserve their scent.
 
Oven Method:

Place your shredded soap in a stainless steel, enamel coated or glass pot or pan and add just enough milk to moisten the soap.  Cover and let the soap absorb the milk for about an hour.  Heat your oven to 175 to 180 degrees and place your pot of soap in the oven.  Check and stir the mixture ever 15 minutes, adding a little more milk each time.  Try not to add more than ¼  cup of milk per pound of soap.  If the soap is very lumpy, you can add dry powdered milk and stir well – this will smooth out any lumps.  Once your soap is ready to pour you can procced as in the Crock Pot method.

Double Boiler Method:

Using the same instructions as for the Crock Pot Method, add your ingredients to a large double boiler over just simmering water.  Check often to make sure your water does not run out.  Also, make sure you cover your double boiler during the melting process.