Letters of Recommendation - Duration Etiquette
It would be normal to have some letters of recommendation from professors at your undergraduate institution.  In my experience, faculty often write such letters for students a few years after they've graduated and will typically keep old letters of recommendation on file as a starting point for an updated letter.  

However, it is also important to have positive letters of recommendation from your current advisor and possibly others at your current institution.  If you don't get such recommendation letters, then this could be taken as a sign that you've done badly at your current institution.