The ornamental design for a sofaframe, as shown and described.
FIG. 1 is a top, front, left side perspective view of a sofa frame showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a right side elevational view thereof;
FIG. 4 is a left side elevational view thereof;
FIG. 5 is a top plan view thereof;
FIG. 6 is a rear elevational view thereof;
FIG. 7 is a bottom plan view thereof; and,
FIG. 8 is a top, front, left side perspective view of a second embodiment of a sofa frame the break lines indicate that the appearance of any portion of the sofa frame between the break lines forms no part of the claimed design, that being the only difference from the embodiment shown in FIGS. 1-7.