IMO spicing things up may be ,just may be, the wrong way of doing things . Well not my way anyway. I think you need to go back to basics again. Perhaps learn how to love each other again and put sex firmly on the back burner. If you can get baby sitting cover then start by having date nights out and relaxing in each others company and enjoy each others company . Better if you can is to get some nights away in a hotel or B & B .Start having meals out , perhaps trips to the cinema and if either of you like dancing find an appropriate night club for your age group.When you are out ,behave like a couple of love birds , play footsie under the table etc Dress to impress as well. ..Communication is a key element as well so its important that you have a chat with your other half first before planning things. Bring a little romance into it as well , buy her flowers . More impressive if you can get them sent by a third party delivery. Perhaps when you are at home you could run a bath for her and pamper her.
The sex side of things will eventually come back over time but don't rush it.
The above is basically what we did to bring the spark back but in our case it was over a much longer period .