What did Yaakov mean when he replied, "You know how I worked on your behalf? How did this counter Lavan's statement?
Seforno: Yaakov was saying that he should stop ascribing his successes to divination, which is rooted in Mazal, but rather to his (Yaakov's) hard work, borne of experience, and intense efforts. 1
Ramban: Lavan knew well how hard he (Yaakov) had worked for him. 2
Bechor Shor: This is a reason to give to me a big wage. (Also, when will I do for my family?!)
Malbim: Do not think that you owe me merely for 14 years of work. There are four reasons why I deserve more. (a) I did not word normally, rather, day and night - "ba'Yom Achalani Chorev, v'Kerach ba'Laylah" (31:40); (b) I worked for you as if it was my own flock; (c) I made you rich - initially your flock was small, and I made it great; (d) Hashem blessed you above nature due to my righteousness.
What was Yaakov referring to when he said to Lavan "Es Asher Avadticha"?
Oznayim la'Torah: It seems that besides tending to Lavan's flocks he also worked a little in his house as well.
What did Yaakov mean when he added, "and what your livestock were with me"?
Seforno: He was referring to the way that he had bound the animals with broken limbs and healed those that were sick, as befits a good shepherd.
Targum Yonasan: He was reminding Lavan how well he had looked after his sheep.
Rashi: He was asking Lavan to recall how few sheep he had handed him (and to note how many they had now become). 1
Ramban: Yaakov made three statements here - He reminded Lavan (a) How hard he had worked for him; (b) How long he had faithfully looked after his sheep; (c) How the few sheep that Lavan initially handed him had proliferated - thanks to Hashem's Berachah.
Malbim: Even though it was your flock, they were with me - as if it was my own flock. Ha'amek Davar - I guarded exceptionally well for your benefit, and to avoid pain to animals.
Gur Aryeh: But the verse seems to mean the way Yaakov worked with the flocks, not the flocks themselves? Yaakov already said above, "My work that I have worked for you" (30:26) and what is he adding here? Yaakov was saying two points - I worked for you with all of my strength; and although I was given little to work with, you were blessed due to my arrival. But see Ramban, who queries the order of the wording in the Pasuk according to Rashi.