You would serve and file a Petition for Divorce which can mirror the legal separation. You can seek the relief granted in the legal separation, but the court is not bound by that order or those agreements.
Actually, if the legal separation is still in effect, in Colorado you can convert that to a divorce decree by filing a motion to that effect, pursuant to CRS 14-10-120 that states you have sent notice to your spouse that you wish to convert the legal separation to a decree of divorce. Nothing about the decree of legal separation is affected by the reconciliation unless you took steps to dissolve the legal separation. You do not have to file a separate petition for divorce.
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