8 puzzle iterative deep search implementation

Question

I have implemented a depth first search (recursive) for the 8 puzzle problem in Java:

protected PuzzleState depthFirstSearch(PuzzleState state) {
        PuzzleState start = this.getStartState(); 
        PuzzleState goal = this.getGoalState(); 
        PuzzleState stop = null;

        int limit = 35;
        int depth = state.getDepth();
        boolean tooDeep = false;

        if (state.equals(goal)) {
            return state;
        } else {
            if (depth == limit) {
                return stop;
            } else {
                Collection<Integer> actions = PuzzleAction.getPuzzleActions();
                for (Integer action : actions) {
                    PuzzleState starter = start;
                    PuzzleState next = state.succ(action);

                    if (next != null) {
                        starter = depthFirstSearch(next);
                    }
                    if (starter == stop) {
                        tooDeep = true;
                    } else {
                        if (!starter.equals(start)) {
                            return starter;
                        }
                    }
                }
            }
        }
        if (tooDeep)
            return stop;
        else
            return start;
    }

I don't know what I have to change to transform it to a iterative deepening depth search. I know that there is no limit for the depth, because it increases in every round. Tried this:

protected PuzzleState iterativeDeepSearch(PuzzleState state) {
        int depth = state.getDepth();
        for(int limit = 1; limit < depth; limit ++){
            depthFirstSearch(state, limit);
        }
}

Does anyone know how to change it to the needed IDS? Thank you in advance!