Just to add/confirm to what's been said. You should not be experiencing that much of a voice loss after a show if you're using your voice right. You may need to reexamine the voices you're using for your characters, doing less things from the throat, nothing too low and especially too high for your voice. You may also look at the mechanisms by which you're being hears - are you miked or are you yelling out from behind a stage hoping to be heard from the back?
Even if you're not looking to do musical performances, a singing teacher/vocal coach will be of huge help as a trained professional will be able to help you learn how to use your voice in different ways and identify things you're doing that would hurt it. Small things you may take for granted like breathing and where you're pulling sound from your body (diaphram vs throat) are all things you'll learn which will be of great value whether you're singing or doing puppet voices.
As for the more immediate question of recovering your voice after a show, here are some various tips but it's important to note that none of these are "cures" or that you should depend on these as insurance of getting your voice back allowing you to damage it more - like most anything else the biggest cure is prevention...but here's the things i rely on as a singer to deal with voice loss:
- REST YOUR VOICE AT ALL TIMES between performances until you're not losing it - even if you have to do things other people think are silly or over the top, you're using your voice in a professional capacity so your dependance on it is important. So if you have to write notes to people instead of talking aloud, it's worth your while over them thinking you're going overboard.
- WARM YOUR VOICE UP BEFOFE A LONG SHOW. Again acting/singing teachers can give you various exercises. This may at first seem contradictory to what i just said above, but the voice is like any other strenously used body part - rest helps it heal between strong periods of usage, but warming up before you put it through extended use helps prepare it for what it's about to take on.
- Drink plenty of warm fluids, avoid cold liquids and dairy products/chocolate. Hot tea with lemon and honey (both of which are great for healthy voices) is best (i'd actually say essential). Soups are also good. Gargling with warm saltwater also helps.
- Take Vitamin C - but also be prepared to use the bathroom more when you start taking more than you're used to. Pay attention to dosage instructions and don't overdo it.
- Keep your throat warm and moisturized - hot steamy showers are good as well as a steam humidifier for the room and i also use a steam inhalent that you breathe into.
- In addition to resting your voice, rest your body. Sleep is your friend. Most of your body's healing will take place once you obtain deep sleep.
- When you DO have to talk in between performaces, talk very low, use your deepest register as your upper registers are usually the first to go and the last to come back. Again your friends and family might think you're being silly trying to sound like an announcer or 6'7 giant, but saving the parts of your voice that you rely on comes first.