You have 2 real alternatives that spring to mind. Firstly, set your aperture to f11 or even f16. The drawback with using smaller apertures is loss of sharpness due to diffraction. Its a trade-off really. The other option is focus stacking. Here you take several shots moving the focus slightly for each shot. You then process them in software. This can work well and give greater DoF than an other process that I can think of. If you already have Photoshop then stacking is available from the later versions. There's a freebie called CombineZM or a commercial program called Zerene Stacker which I have used and works well.
HTH