The cost of glass replacements for exterior doors may vary depending on what type of glass, the glass size and the patio door you intend to restore. Although these patio door replacement glass features may be more costly than standard options but using tempered or laminate glass is much safer than regular glass. A double pane window or door is also more expansive to replace than just a single pane .A sliding door glass replacement is more costly simply because it cost more to replace the entire glass pane for a sliding door than an average window or glass door panel.