I don't know the nature of your texture so this might not help.  Something I've done in the past is enlarging the the original in the paint program by doing this:

Example: If your original texture image is 1000x1000 pixels.  Open a new project at 2000x2000 or larger.  Copy/paste your texture to the new canvas.  By rotating the layers or clone brushing (rubber stamping) along any obvious tiling you can create a much bigger source file for your texture.

But a AS said when you try to use it on an infinite plane, you will usually see the repetitions.