[Apth]

It's easy to get into a losing streak if you expect to lose.
When you have a free couple of days, dedicate them to Starcraft. No TV, no Facebook, nothing. Just Starcraft.
Wake up in the morning, have breakfast, play Starcraft. Have lunch, play more Starcraft. Stop for dinner, play more Starcraft. Go to bed at a reasonable hour. Wake up the next day, play more Starcraft.

After your Starcraft marathon, don't play for a couple of days, you'll be doing analysis. Check your win/loss ratio. Has it improved? Have you trashed it? Check your replays - which you have saved, every single game. For each replay, write down your build, and your opponents build. By doing this you can identify which openers you are strong against, and which ones are your weak points.

Once you've identified what you're strong against and what kicks your ass, you need to figure out why. Lets say you've gone through your replays and realised that any time a Protoss player goes Forge Fast Expand, you lose. Why is that? Is it because his economy overtakes yours? Are you not scouting enough, and you aren't ready for that giant first push?

Find commonalities in your losses. Figure out how to overcome them.