[ChipFish]

Good question...
First thing you do if it is effecting your play... and it will if your bankroll is being severely diminished by these bad runs, is to step aside.
Good for you.. You've done that.

Next is to re-evaluate.
You no longer have the bank-roll for 2/4.
With 140 you actually don't have a decent roll for 1/2.

I see 3 possible scenarios here.
A) Put it all in to 3/6 and go for broke. [chances are good you will go broke]
B) Re-Load [Personally I think this is the best option.
C) Play some baby no-limit tables.... Either the $25 at Party or a 10cent/25cent blinds table somewhere else. (It will take some time but you should have a decent roll again within a week or two).
[This is also a good idea, it will just take you quite a bit longer to build up a roll rather than just re-depositing.]

Unfortunately you have run into some crap cards...
This is the "variance" that everyone is talking about... You always miss the flop, and you always seem to get sucked out on.

Just ride it out and stop playing in limits you are not properly bank-rolled for.
Good luck.