Backslide

Verb

 * 1) To regress; to slip backwards or revert to a previous, worse state.
 * 2) To shirk responsibility; to renege on one's obligations or commitments.

Thesaurus
cock, defect, degenerate, desert, err, fall, fall again into, fall astern, fall away, fall back, fall behind, fall from grace, get behind, go astray, go backwards, go behind, go wrong, have a relapse, jerk back, lapse, lapse back, lose ground, pull back, recede, recidivate, recur to, regress, relapse, retrocede, retroflex, retrograde, retrogress, retrovert, return, return to, reverse, revert, revert to, sink back, slide back, slip, slip back, tergiversate, trip, turn, yield again to