Flushing is about all you can do.

It's pretty hard to kill an established crape myrtle. Unless it was planted new last year, it will likely recover from whatever is ailing it.
Is it making more new leaves yet?

debndal ,Actually I planted it last Spring. Yes, there are a few new leaves that are a pale green ...no brown tips. So you think it might be ok ?

Yes, I think it will be fine. Just be sure it has enough water thru the summer and don't fertilize it with chemical ferts the rest of the year. You could maybe foliar feed it when it gets more leaves with either miracle grow, or I use liquid seaweed or fish emulsion. Do it on a cloudy day or late in the evening if humidity is low and it's warm enough to evaporate fairly quickly.
If you really have deplete soil you could put some superphosphate around the roots in January next year. Helps with vigor and bloom.

I suggest you have your soil analyzed. The cost is well worth it.

I transplanted a crape myrtle in early spring and the leaves are looking exactly as you describe. I think it is transplant shock meaning -- the feeder roots have not yet had time to established to properly nourish the plant. I'm not worried about it so don't worry about yours either.

Happy gardening!

Thanks everyone. Glad to know it is probably going to be ok. Really appreciate all the input!