Whenever I am working up a new effect or routine, I work at it for long chunks of time until I get it down to performance level. After that, I am left with the problem of keeping it at that level. I don't do this for a living so I'm not doing the routine 50 times a week. My normal method is to simply run through the routine one to three times a week. How often do you need to practice or perform a routine to keep it fresh and up to standard? What about effects you learned 10 years ago and don't perform regularly any longer? Do you just lose them?

Magic has been a hobby of mine for years.
Being in a similar situation as you, I run through a few, more complicated tricks about once or twice a week. If there's a family gathering coming up I will practice more.

For the most part I've learned to keep the effects fairly simple. These are often quick, impromptu type tricks that can be combined into a routine when need be.

There are a few tricks and routines I learned long ago that I don't forget and keep fresh. Others I have lost or need to go back to the source and refresh my memory.

How often you practice depends on your goals.
Do you want to go pro? Are you OK with being a hobbyist or trickster? Etc?

Having occasionally lost a thing or two, I now put them on video tape with my own explainations similar to eduicational tapes you'd buy in the various magic DVD's.
That way not only do I have the bare bones but in case there are some moves I don't often use I can teach tem to myself.

The ones I use often I have not done this with - hopefully as I grow older this does not prove to be a mistake.

Frank Tougas

I have pondered this too for a long , long time.

I have practiced certain routines thousands of times until I can do them forwards and bacwards in my sleep. LITERALLY! You would think that at that point they would be burned into your brain so that you couldn't forget them if you tried.

But guess what? Take those same routines that are "permanently" burned into your brain, and don't review them or perform them for a year or even a few months and guess what happens? You guessed it! All that hard work, blood sweat and tears and mental energy has gone bye bye. You stumble over trying to remember the moves and patter you once knew intimately. You suddenly go from being "Mr magic" to being "Mr retard"

All I can say is it's not like riding a bike....

Doing it once a week should be enough, if the routine is where it should be. If not, rehearse it with a video camera, make observations, make one little change with each rehearsal of the effect, until it is ready.

When you think of a way to improve a routine, or think of a weakness in the routine, write it down. It will come in handy, later.

One of the keys to remembering a routine is to simplify it and document it, so that when you solve a problem with the routine, that problem need never happen again. I stop and devise a memory hook, to help me remember how the routine should go.