slip back (?.)
- backslide
- cock
- degenerate
- deteriorate
- disimprove
- fall
- fall again into
- fall astern
- fall back
- fall behind
- fall from grace
- get behind
- get worse
- go backwards
- go behind
- grow worse
- have a relapse
- jerk back
- lapse
- lapse back
- let down
- lose ground
- pull back
- recede
- recidivate
- recur to
- regress
- relapse
- retrocede
- retroflex
- retrograde
- retrogress
- retrovert
- return
- return to
- reverse
- revert
- revert to
- sicken
- sink back
- slacken
- slide back
- worsen
- yield again to
