getting rid of signal 0 / storing signal values

Hello,
This is probably a super simple MSP question, but I can't figure it out.

I am receiving a signal going from 0. to 1., and eventually 1. to 0. When the incoming signal reaches a low threshold (0.3 in the example), I want to output a signal 1. When the incoming signal reaches a high threshold (0.7), I want to output a signal -1.
My goal is to create a ping pong (palindrome) playback for groove~ (in MSP all the way through), so I need:
From 0. to 1.:
- 0. to low threshold > output 1.
- low threshold to high threshold > output 1.
- high threshold to 1. > output -1.
From 1. to 0.:
- 1. to high threshold > output -1.
- high threshold to low threshold > output -1.
- low threshold to 0. > output 1.

Here is was I have so far:

It's basically working except there is this unnecessary 0. in between the two thresholds.
Is there a way to get rid of a signal value in MSP? (like sel in max)
Or is there a way to store a signal value so it is sent later?
any help would be appreciated!
thanks
Florent