Yes, replace 2 15 amp breakers with a double pole 60 amp breaker higher up towards the top than any of the single breakers with a balance of double pole breakers on both sides of the panel. Depending upon the length, run #8 or #10 thhn/thwn for each hot conductor to the main lugs of the subpanel. Run a white neutral wire from the neutral bar to a non bonded (do not screw in the green screw) neutral bar in the subpanel. Run a ground wire from the neutral and ground bar(which are combined in the main panel) to a new and separate grounding bar in the subpanel. (a 3 wire with ground as the 4th in sheathed electrical cable may be alright instead of thnn/thwn). The subpanel must have separate ground and neutral bars which is different than in a main panel. Also the neutral bar in the subpanel should not be bonded to the panel case itself like it is in the main panel.